The idea that our language is going to the dogs is a pedant’s meme that goes back at least as far as Seneca.
Perhaps you had a teacher (or a boss or an editor) with a prescriptivist bent, someone who holds certain principles of language use to be immutable laws, such as ‘Never start a sentence with And or But’ or ‘Always use a comma after “which”’.
We all have a few of these peeves rattling around our heads, but it is the mark of the true prescriptivist to turn them into in an ideology.
Society’s inevitable failure to adhere to such ‘rules’ with total compliance is taken by the prescriptivist as evidence of declining standards, a society that is traducing the language of Shakespeare in its race to the bottom (See The Daily Mail for more of this sort of thing; for more background to the conflict, see Proper English by Ronald Wardaugh, or The Language Warsby Henry Hitchings).
Peeves are not rules
Unfortunately, the gulf between those who preach about language in this top-down way and those who actually dedicate their lives to understanding how language works continues to yawn.
Prescriptivists carry around with them a ragbag of unexamined diktats which are social rather than linguistic in force: not ‘knowing’ that it’s poor form to verb a noun or split an infinitive, for instance, is taken as evidence of a second-class mind or of someone who attended the wrong school.
But these are not rules, so much as superstitions or shibboleths.
