Less/fewer is probably a lost cause, and a little bit of why is this kind of useless correction. If those who correct can’t or won’t explain why one is correct over the other, then it simply isn’t.
ETA: a fun comment below points me to a running joke I was unaware of; my apologies if this was an instance of it that I missed. I am not really a television person but this feels like a significant bit of cultural ignorance on my part.