It's not prescriptivism, you're misusing that word, what's actually happened here is that you've fallen for a political misnomer or a series of political misnomers

Liberalism has a basis in historical socio-economic practice that runs into the present day, its multiple schools of thought from; social liberalism, ordoliberalism, neoclassical econ, Keynesianism, the Austrian school etc. define and shape not only the contours of higher learning, but the whole political matrix of the entire earth, and all those schools make a mockery of the common "colloquial" understanding

The so-called "presciptivist" definition is the one that accurately describes the liberalism in the heads of the powerful, the wealthy, the influential, their mentors, their brokers, their guard dogs, their scientists, their theorists, their planners.....basically it's the liberalism that has actual power and acts as the software for capitalism's hardware; and I'm telling you now friend, you won't find that info in a dictionary

Maybe I'm just so indoctrinated that the knots and twists don't feel all that knotty or twisty.

Really? You think it's worthwhile to play No True Scotsman with a half-dozen different flavors of liberalism? It doesn't matter what you or those people claim to be or believe; it's the ideas, values, epistemology, and actually existing political structures that they defend that truly define who they are