I honestly hadn't ecen realized that is a thing.
I have noticed a shift through the years though, and that is that some decades ago, anime was attacked by people that didn't understand the culture emerging from it. Parents grew up with Kimba and Candy-Candy not knowing they were anime but were alarmed by the Pokemon craze and people cosplaying and stuff. Since it was kind of niche, most people saw it odd.
Lately, it is more like the same people in anime attack other anime and groups of people because of their tastes or subculture. The gatekeeping started. You're not a true anime fan if you haven't watched this anime, or if you don't agree that that one is rubbish. There's a counter-culture and questioning just how over hyped are some "classics" and how others qualufied as trash have merits to them. I think questioning is good and discussions to explore that can be quite entertaining. The problem comes with impossing opinions as facts and attacking others due to them not aligning with your views.