Linguistic prescriptivism, a.k.a. the majority of this thread. Correctness is determined by usage, not arbitrary convention. Language is constantly changing and evolving whether you like it or not.
You can say “x is wrong”, but, if it’s in common usage, is it really? The English language is full of things that were once wrong but have since become acceptable. Singular “you” was once wrong, yet it fully replaced “thou” long ago.
It was once ungrammatical to not decline English nouns, but the vast majority of English speakers nowadays don’t even know what cases are. We did away with cases almost entirely many centuries ago, preserving them now only in certain pronouns and in the genitive 's.
In addition to changing grammar, meanings of words constantly shift, too. “Pineapple” once referred to those things that grow on pine trees, because they’re shaped sorta like apples and they grow on pine trees. Then the same word got used to refer to a spiky fruit, because apparently some people thought they looked like the pine tree things, and now we call the pine tree things pinecones. Semantics shift in weird ways sometimes – and in less weird ways, too. “Adventure” originally meant good fortune or luck, but who uses it that way now?
Just imagine how everyone must have been up in arms about these changes in how people spoke! For as long as language has existed, people have taken prescriptivist stances and even claimed language change was desecrating the language. That’s never been the case, though.
Language change is entirely natural and normal. It’s a constant process which cannot be stopped so long as a language remains living, and it is neither good nor bad. It is simply change. No form of a language is inherently superior or inferior to another.
If you don’t like the thought of the English language changing, go read Beowulf in the original Old English. Heck, read Chaucer. See how much you can understand of our language before it underwent a myriad of changes once thought egregious that have since become normalized.
If language change is bad, then language has been declining for thousands of years. Even Latin, then, regarded by many scholars as a language of ideal, is a thoroughly debased form of Proto-Indo-European. English - MODERN English esp. - is the unintelligible babble of barbarians.
Or, you know, language change should be accepted and embraced, bc 21st-century English is no better or worse than 20th-century English, which is no better than Middle English, Old English, Germanic, Latin, PIE, whatever. There’s no contest. All language is legitimate and good.
Actually, one more thing, just because I know someone’s going to try and call me out on this: I’m referring specifically to spoken language here, which means this all applies to written language insofar as it is a representation for the language we speak.
Spelling and punctuation are governed by fixed, standardized rules, and there are absolutely right and wrong ways to spell words and punctuate sentences. So, no, “they’re”, “their”, and “there” are not interchangeable, even though “he and I” and “him and me” are.
Spelling and punctuation are conventions of writing not intrinsic to the verbal content, just as the Roman alphabet has no intrinsic connection to the English we speak. It’s simply a convention we adhere to when transcribing a written representation of our spoken language.
I have no qualms with such conventions being standardized and resistant to change. Again, writing is a REPRESENTATION of language – not the language itself – and it doesn’t undergo that same constant evolution even when allowed to.
Yes, writing systems do evolve over time when not restricted by imposed standards, but the rate of change is MUCH slower. It’s really only the spelling that’s prone to immediate variation, and, really, there’s no reason for everyone to be spelling the same words differently.
Standardized spelling, IMO, is a good thing, because it facilitates legibility and clear communication.
That said, a sort of natural evolution in how we write has come about on the internet, and that isn’t inherently wrong, either.
The internet and other channels of text-based communication have led to the formation of subculturally-bound dialects which do defy written language standards. Textspeak and tumblrspeak (heck, even 1337speak, if that’s still a thing) are not inherently ungrammatical.
These unique sociolects – including the disregard for punctuation and capitalization, spelling variations, “intentional typos”, etc. – are entirely acceptable and, dare I say, even correct within the specific contexts in which they are used. Nonstandard does not mean wrong.
Anyway, that was my disclaimer plus tangents I didn’t mean to go on. You’re welcome.