I can answer this question! And I'm not, nor ever have been, FA but I have the comment Karma and I'm following the rules.
The disdain actually comes from the want to point out why this condition exists, but unfortunately the people suffering from it call the cause the symptoms. The VAST majority of people on this subforum are actually pretty fucked up and need medication / professional help, and I don't blame them for having trouble connecting with people because they're injured human beings. They were born injured, nobody has helped them, and it has festered into the later years of their life causing great harm to them.
Then you have young crazy people like alyssaandadam. Personally, I'm really glad the Internet didn't exist when I was that young. Holy shit he's going to look back on this forum and feel ... remorse? I think? He's so deep in his own bullshit even FA hates him. Whatever mix of crazy is happening there I chalk up to being really god damn young and needing somebody in real life to talk to.
There's also the absolute contempt for self improvement in this forum. Most humans are trying some form of self improvement. We really do, from the most attractive woman on the street to the bald guy dating her. You really need to become comfortable with improving yourself, and it sounds bad but you also have to do it with only yourself as the goal. Going to the gym to escape FA is really missing the point, and you won't follow through with the time necessary to see improvement so fuck it.
Finally, and this is the hardest thing to hear - There are A LOT of products of the Internet and post gen-X here. If I counted the times I read anime and video games on this forum and traded it in for nickles I would be retired. I love video games (was born in the age of the original NES, Contra, and the gold Zelda cartridge), but I also love going outside, having a job, working out, reading stupid shit so I can connect with other people about stupid shit, going to bars and saying stupid shit to people while they say stupid shit back, and following dumb sports I can't play. It takes an amazing amount of self control nowadays to go outside and deal with people face to face with the Internet and the gaming culture giving people just enough connection to avoid intimacy. Add in some insanely different cultural relics people can access immediately that in no way match the culture they live in... and well... this happens.
Quite frankly, FA is nothing more than untreated mental illness and a high exposure to a counter culture that most people don't give a fuck about in western civilization. You've never actually been forced to be treated for your problems, or told to stop watching that dumb shit / playing that game, and go outside. The assholes on tumblr have the exact same ailment, but go about it in different ways. A good example is the creepy guy that talks about adopting a baby girl incessantly here. He absolutely doesn't understand why the outside is disgusted by a barely functional male, with no connection to the opposite sex, raising the opposite sex from birth. Does he really think we're all stupid enough to not know he's going to use that child as a stand in for his problems with women and token of his anime / game girls he fantasizes about? Does he really think we as a society are stupid enough to give him that child and watch the amazing problems that are going to erupt in 12-14 years? Assuming he can even keep a child alive that long.
I don't even think this forum could understand how fucked up it is to give women number grades outside of a bar with your asshole friends, and then demand feedback because you have standards. We all have standards, but it's pretty juvenile to throw it back in societies' face by talking about never getting an 8 and why are fat women dating attractive men because you're better looking than her. Nothing is stopping you from going to a gay bar and finding you an attractive man, and everything is stopping you from connecting with the opposite sex because you really are being an asshole. And I don't think you just say it here. I'm sure you say it out loud, whenever you do go outside, and when people get offended you go into a rant about having standards. People don't do that in polite company, and by polite I mean nearly everybody you will ever meet.
And that's your answer. This forum is a mirror into the warnings our parents gave us, and to a large extent a view on the mental illness situation in the united states. We look at homeless people with pity and try to help them, and that is our view on this forum. You don't deserve it, but you can't escape it because you don't have the tools - both mentally and through society - to make you "normal".
What you see as disdain and an attack most people see as legitimate help that can put you some place functional if you stay at it. However, I can't teach a mentally ill homeless guy how to get a job and build a 401K ... and that's where help fails and turns into adding to the problem.