Before I answer your question about liberals, let's start by deconstructing the term "authoritarian."

In "On Authority", Engels says the following:

A revolution is certainly the most authoritarian thing there is; it is the act whereby one part of the population imposes its will upon the other part by means of rifles, bayonets and cannon — authoritarian means, if such there be at all; and if the victorious party does not want to have fought in vain, it must maintain this rule by means of the terror which its arms inspire in the reactionists.

while Bakunin and other anarchists in the 1st international, on occasion, did argue that anarchists reject "all authority" they, as Carole Pateman correctly notes, "tended to treat 'authority' as a synonym for 'authoritarian,' and so have identified 'authority' with hierarchical power structures, especially those of the state. Nevertheless, their practical proposals and some of their theoretical discussions present a different picture. Bakunin, clearly, did not oppose all authority but rather a specific kind of authority, namely hierarchical authority. This kind of authority placed power into the hands of a few. For example, wage labour produced this kind of authority, with a, quote,

"meeting [...] between master and slave [...] the worker sells his person and his liberty for a given time.

Lenin said that the state is merely an instrument for the suppression of one class by another, which is why he believed in seizing the state rather than destroying it. That is, replacing a Class Dictatorship of the Bourgeoisie (Capitalism) with a Class Dictatorship of the Proletariat (Socialism), which would eventually become Communism.

So, all that being said, my issue with liberals, is less that they are "authoritarian" and more that they are reactionary. The class dictatorship of the proletariat may be called "authoritarian" just like the class dictatorship of the bourgeoisie (Capitalism), or the class dictatorship of the landed aristocracy (feudalism). So the real question is, whether the authority is reactionary or revolutionary. The authority of liberals was at one point in time revolutionary, specifically in the context of the end of feudalism. The replacement of the feudal aristocracy by the bourgeoisie was, if nothing else, historically progressive. However, the liberals and conservative bourgeoisie are both reactionary, and the socialists are progressive.

The bourgeois revolutions, such as the French revolution, were looked upon by Marxists as historically necessary but ultimately outliving their purpose. Marx, Engels, Lenin, Stalin, Trotsky, all agreed on this:

Marx:

The gigantic broom of the French Revolution of the 18th century swept away all these relics of bygone times, thus clearing simultaneously the social soil of its last hinderances to the superstructure of the modern state edifice raised under the First Empire, itself the offspring of the coalition wars of old semi-feudal Europe against modern France.

https://www.marxists.org/archive/marx/works/1871/civil-war-france/ch05.htm

Engels:

In my opinion (and that of Marx) the book contains the first specific and correct account, based on a study of the archives, of the critical Period of the French Revolution, namely from 10 August to 9 Thermidor. […] The whole French Revolution is dominated by the War of Coalition, all its pulsations depend upon it. If the allied army penetrates into France – predominant activity of the vagus nerves, violent heartbeat, revolutionary crisis. If it is driven back – predominance of the sympathetic nerves, the heartbeat becomes slower, the reactionary elements again push themselves into the foreground; the plebeians, the beginning of the later proletariat, whose energy alone has saved the revolution, are brought to reason and order.

https://www.marxists.org/archive/marx/works/1889/letters/89_12_04.htm

Marx, Engels both thought the French revolution was of a progressive character when it took place, destroying the semi-feudal Europe and giving birth to bourgeois Europe. A necessary historical development to make socialism possible in the future.

Stalin:

As modern history is the most rich in achievements and as it is this which is the most important thing in the modern history of bourgeois countries, if one considers the period preceding the October Revolution in Russia, it is the victory of the French Revolution and the affirmation of capitalism in Europe and America which should be emphasized and so we believe that it would be more valuable to have a manual of modern history beginning with a chapter on the French Revolution.

The biggest failure of the summary seems to be that it does not emphasize clearly enough the great difference between the French Revolution (bourgeois revolution) and the October Revolution in Russia (socialist revolution). The central theme of a manual of modern history must be precisely the theme of the opposition between the bourgeois revolution and the socialist revolution. To show that the bourgeois revolution in France (as in all other countries) in liberating the people from the chains of feudalism and absolutism, imposes on them instead, the chains of capitalism and bourgeois democracy, whilst socialist revolution in Russia broke all chains and liberated the people from all forms of exploitation and that is what must be the thread running through a manual of modern history.

https://www.marxists.org/reference/archive/stalin/works/1934/08/09.htm

Trotsky:

The Great French Revolution was indeed a national revolution. And what is more, within the national framework, the world struggle of the bourgeoisie for domination, for power, and for undivided triumph found its classical expression.

[…]

Jacobinism is now a term of reproach on the lips of all liberal wiseacres. Bourgeois hatred of revolution, its hatred towards the masses, hatred of the force and grandeur of the history that is made in the streets, is concentrated in one cry of indignation and fear – Jacobinism! We, the world army of Communism, have long ago made our historical reckoning with Jacobinism. The whole of the present international proletarian movement was formed and grew strong in the struggle against the traditions of Jacobinism. We subjected its theories to criticism, we exposed its historical limitations, its social contradictoriness, its utopianism, we exposed its phraseology, and broke with its traditions, which for decades had been regarded as the sacred heritage of the revolution.

https://www.marxists.org/archive/trotsky/1931/tpr/rp03.htm

Lenin, furthermore, viewed Socialism as, among other things, the proletariat seizing upon the state capitalist monopolies and the state machinery.

For socialism is merely the next step forward from state-capitalist monopoly. Or, in other words, socialism is merely state-capitalist monopoly which is made to serve the interests of the whole people and has to that extent ceased to be capitalist monopoly.

https://www.marxists.org/archive/lenin/works/1917/ichtci/11.htm#v25zz99h-360

To make things even clearer, let us first of all take the most concrete example of state capitalism. Everybody knows what this example is. It is Germany. Here we have “the last word” in modern large-scale capitalist engineering and planned organisation, subordinated to Junker- bourgeois imperialism. Cross out the words in italics, and in place of the militarist, Junker, bourgeois, imperialist state put also a state, but of a different social type, of a different class content; a Soviet state, that is, a proletarian state, and you will have the sum total of the conditions necessary for socialism. Socialism is inconceivable without large-scale capitalist engineering based on the latest discoveries of modern science. It is inconceivable without planned state organisation, which keeps tens of millions of people to the strictest observance of a unified standard in production and distribution. We Marxists have always spoken of this, and it is not worth while wasting two seconds talking to people who do not understand even this (anarchists and a good half of the Left Socialist-Revolutionaries). At the same time socialism is inconceivable unless the proletariat is the ruler of the state. This also is ABC. And history (which nobody, except Menshevik blockheads of the first order, ever expected to bring about “complete” socialism smoothly, gently, easily and simply) has taken such a peculiar course that it has given birth in 1918 to two unconnected halves of socialism existing side by side like two future chickens in the single shell of international imperialism.

https://www.marxists.org/archive/lenin/works/1918/may/09.htm