I remember listening to a person comment on one of my lithographs at a group art show I participated in. The guy was tearing up the print, talking about how it wasn’t art, since the subject of my art (it was a big portrait of Einstein) wasn’t sitting there for me when I created it.
Kinda funny really, I just don’t let this kind of stuff bother me. I just smile and nod and say “thanks for looking! I’ll think about that”.
But yeah, people that tell you what you should or shouldn’t do, well, shouldn’t.