I actually don't know what you're even talking about, sorry.
In nearly every online community* I've been a part of, anime has been the butt of the joke. Just this morning, I logged into a chatroom and said hello and was greeted by someone making fun of anime, at my expense!, because I'm vocal about my love for anime.
People make these jokes because of the shitty things that are part of the medium we call anime. Fanservice, creepy loli shit, etc. I'm also vocal about hating that element of the medium, but it doesn't matter. It's still a joke that I like it in the first place because it's creepy and gross. It's all bad because High School of the Dead exists. Doesn't matter that a lot of my favorite stuff has none or very little of it. It's still a joke.
In most cases, I just try to laugh it off, because, you know, people aren't trying to be malicious when they say these things. But the constant onslaught is bound to wear anybody down, right? And then a thread like this occurs where people are being completely serious, not joking, and utterly dismissive of the entire medium. Understandable, but still frustrating.
So while I understand where you're coming from when you accuse people of being "shrill and overly defensive", and how that's a repulsive behavior, I really do understand... Maybe you should try to understand where anime fans are coming from when they get "shrill and overly defensive" in the first place?
*God I don't even want to think about trying to talk about anime in most of my real-life social groups.