D’you know, I think a huge problem with this is English. English, oddly for an Indo-European language, is basically isolating in its grammar. Of course, what with the waterbed hypothesis this doesn’t mean it has less grammar, it just means that a lot of it is in context, subtle, and sort of… analog?
Let me explain: My native language (as well as one or two others I’ve some passing proficiency in) is heavily inflected. It has loads of very strict grammar rules and if you ignore them you don’t sound uneducated, you are simply very difficult to comprehend. Cases, agreements, and such are very important.
This means that there’s really no such thing as a grammar snob, though orthography does attract the errant busybody from time to time.
Now, English has rules but these are socially determined (English has no standards body which is by no means usual), and they are fuzzy and context sensitive and as a result not using them doesn’t just lead to gibberish but instead degrades the expressiveness of language smoothly (analog, y’see) more and more the fewer rules get used.
Now, I’m a foreigner and English is, evidently, my second language and this no doubt has a severe influence on what the Germans call Sprachgefühl: my sense of the language may not be the sense a native speaker has. That said, I find the stilted ungrammatical English that the grammar snob decries to be, ah, poorer in meaning? Less expressive.
Certainly, there are rules that are arbitrary and noisome to the linguaphile: the splitting of infinitives and ending sentences with prepositions are two standard examples. Not all rules improve language. But some are of crucial importance. The semantic drift that destroyed the word ‘awesome’ for instance, and reduced to a synonym for ‘good,’ has left us with no word meaning ‘awesome’ as it once stood. That, I think, is an unmitigated ill.
But, ultimately, I think that grammar snobbery isn’t about that. In some instances it is about exerting social power and using correct (or ‘correct’) grammar as a shibboleth to distinguish class, certainly. But in a lot it is simply about an aesthetic sense of language: certain ungrammatical forms, certain misuses of words, certain ways of crafting a sentence simply strike people as ugly. I find bureaucratic English almost painfully hideous, for instance, and I’ve a similarly visceral reaction to your average YouTube comment.
I think language should be beautiful and saying nothing as it gets mutilated just so you can expiate the guilt of your own privilege to no actual benefit of the underprivileged strikes me as selfish myopia.