For example, is using "they" instead of "he/she" when you are uncertain of gender bad grammar or acceptable? Many sources are beginning to consider it okay.
That's curious. I do use "they" when unsure of the gender. Always thought this was indeed the correct way. The habit of separating words with a slash is what I was told is not proper English. There's another option I've seen mentioned briefly once. Use "she". But that always felt like positive discrimination to me. Besides it's often an horrible option because the reader may not get the hint the writer is unsure of the gender.
In any case these type of language issues aren't exactly what I was trying to hint at. I think they predate the mass usage of the Internet. Horrible language has its modern origins perhaps on SMS.
Instead I was thinking about the loss of meaning through overuse of certain words, or the actual destruction of words meaning, not by natural language evolution, but by improper usage.
For instance, during the early 90s no one had any doubts about the differences about hackers and crackers. The distinction was (and still is) meaningful. However the proliferation of non specialized media often using the word "hacker" to mean either one, ended up removing from our vocabulary a good and useful word.
Similarly the overuse of the word "epic" to mean anything one might like, regardless of actual degree, has reduced the word actual impact and robbed us of a real word that could be used if indeed we felt something had a truly epic proportion. The word lost most of its meaning.
Generally speaking the internet has reduced our vocabulary. Or change it in ways that, despite seen as a natural evolution by some, I feel are less then healthy. Language evolution has been bringing us richer vocabularies, not poorer ones.