If kids want to call metalcore "screamo" then why don't we just let them?

I mean 2nd wave metalcore like BMTH and Asking Alexandria etc, kids seem to think that's screamo, if they really want to take an old word and make it mean something else why don't we just let them, instead of getting mad and saying "NO, screamo is bands like saetia, pg99 (some random obscure band from the early 90's) etc"?