I think I understand the reactionary critique of democracy fairly well. It basically consists of the following:

• democracy is over-sanctified as a theoretical concept/ideal, and is a sham as it has actually been practiced
• It's impossible for large complex societies to be horizontally organized; they'll always be hierarchical, and the people at the top will never be entirely accountable to the people at the bottom. There will always be an elite.
• The reason that some countries are richer and more prosperous than others isn't because they're more democratic, it's because (a) they have better institutions regarding private property & rule of law, or (b) they just have more human capital
• some people are just morally/intellectually better than others and deserve to have more political power (e.g. right-wingers on Twitter, such as Matt Walsh, who say things like "you should have to pass a civics test in order to vote" or "voting should be restricted to people above a certain IQ/net worth")

However, I do not feel like I understand the Marxist critique of democracy very well. I know that leftist/Marxist skepticism of democracy (or at least liberal democracy) exists, but I don't really feel like I know what the full argument is. All I know currently is that I've observed internet leftists make various small individual assertions about democracy that, although I think they're mostly true, don't really come together to form a complete vision, and sometimes even contradict each other. These various assertions include the following:

• The US claims to be a democracy but is really more of an oligarchy
• the US was never a democracy
• bourgeois democracy can never be authentically democratic
• liberal democracy is really just colonial herrenvolk democracy and is too historically related to colonization to exist without it
• the bourgeois revolutions of the Enlightenment era were overrated
• democracy is kind of oversanctified and unachievable, and has really been turned into part of the liberal civic religion in Western countries; large societies are never really democratic (this is basically agreeing with the reactionary critique that I described above, at least parts of it)
• Democracy metrics/indices such as this one are basically just meaningless, contrived Western propaganda. It's impossible to know whether any country is really more democratic than any other one.
• China, Cuba, North Korea, Syria (maybe?), Russia (maybe?), and Iran (maybe?) are democratic, and so was the Soviet Union; they just have/had different democratic processes that seem strange and illegitimate to Westerners because of propaganda & cultural gaps.

I think all of the above are true or possibly true, but it seems unclear what's actually being argued for here. In particular, it seems like sometimes the argument being made is "democracy is good and worthwhile, but Western countries aren't really democratic", and other times the argument is "actually democracy is an illusion and not worth aspiring to in the first place".

I feel like I'm missing something here. Can anyone enlighten me? Is there a good text that makes this clear? (I'd prefer something short, like 2,000 words or so, but if you know a book that's relevant you can recommend that as well.)