Remember the Lobster, yo. In a typically can't-tell-if-it's-annyoing-or-really-just-funny-but-not-ha-ha-funny-just-kind-of-chortle-to-yourself-funny way David Foster Wallace gives a pellucid outline of the prescriptive versus descriptive grammar wars. Look at it. I offer no historical facts or figures.
(I'm tired today.)
When I was in high school I remember English teachers wielding a thing called a rubric. Sometimes we'd discuss what color was the rubric: reddish toupe? salmon? pink? As a totem we failed to understand the rubric; its power washed over our writing like (salmon-colored) nuclear waste. I hated rubrics. They told you what the limits were of correct and incorrect interpretations of Grapes of Wrath. I almost always fell in the high-upper-correct range of things, but still. I was no Jim Casey (same initials as Jesus Christ! A Moses-like figure! Land of milk and honey--that's an allusion!); I didn't rail against the system for the people, my classmates, the nonpretentious, unread masses. I just hated to be told what was right.
College: I read me some Saussure, Derrida, Fish, Barthes. Boom! Zap! Pow! Wham! like superheroes all rubrics were before my eyes smashed like so many nameless criminals who never had a chance. Is there an essential meaning to words? The signifier and the signified have no essential connection. Why does the teacher call on you when you raise your hand? Not for any good reason than she's just used to doing that. Don't even get me started on dead authors and systems of differential signs whose meanings are always differed.
(I'm about to fall asleep. To sleep: passive or active verb?)
Pure nihilism. Unadulterated nonsense. Without tradition...well society is nothing, meaningless. Rules! We need rules!!!
(Warning: Elliptical argument ahead, behind and all around you.)
(Here's the money shot, right here.)
I'm afraid descriptive and prescriptive grammar are almost equally conservative. Descriptive grammar (I haven't even defined it!) is a school of meta-grammatical thought that thinks our rules of usage should be dictated by how people actually use language. Prescriptive grammar is a school of meta-grammatical thought that thinks our rules of usage should be dictated by dead white men whose first language seems to be Latin.
Society has been more or less dominated by a prescriptivist-type of grammar since society existed. As such, descriptive grammars tend to describe the status quo. There's a certain fluidity to grammar that both schools of thought accept, I think. That's why stupid-ass words/abbreviations like LOL and baby momma are in Webster's Dictionary.
By the way, Shakespeare wrote in modern English. Zora Neale Hurston wrote in modern English. You figure it out.