Well you couldn't very well be caught dead saying anything, could you? Which is just an example of the fact that we use language in a way which is not strictly tied down to hard logic.

Language changes. Some of the changes are sad, because we lose things on the way. I'm sure that if I'd been a Roman I'd have got very irritated at the way these barbarians were speaking a bastardised version of my wonderful language.

They'd go around ignoring all the rules, abandoning all the carefully articulated constructions that made for an elegant and precise language, which could get an incredible amount of information into a very small compass. Instead of poetry all you'd get would be these clumsy grunts and hisses.

Eheu fugaces!

But in time things settled down, and linguists found that these strange barbarian languages that had evolved did in fact have rules, even though they weren't the same as the rules of Latin.

Language always has rules. They may not be the same as the ones you're used to, and they may seem to be constantly changing, and you don't understand them, and it looks as if there aren't any rules, but the rules are there all right. If there weren't rules it couldn't be used as a means of communication.

I think it makes sense to try and resist changes that rob the language of subtlety and beauty, but not because they are "wrong", because they are clumsy and ugly. And just because there's a fad for some innovation it doesn't mean it'll stick around. But there's no good thinking that there is a permanently correct language that isn't going to alter out of all recognition over time.

As for the gender stuff - using "they" for "he or she" in the right context is a perfectly sensible thing to do, and it has been done for at least the last century and a half. Even if it, using the plural form instead of the singular is not essentially different from what we all do when we say "you" instead of "thou".

"If anyone wants to learn about folk music, they would be well advised to try the Mudcat."

"If anyone wants to learn about folk music, he or she would be well advised to try the Mudcat."

Two ways of saying the same thing. I think the first form is actually better English.