You make a lot of valid points in this post. It's a difficult issue because people can become jaded by those that just use an illness as an excuse for questionable behaviour. But that people are so quick to judge concerns me as I see it regularly online within fandom.
I suffer with mental illness(diagnosed with depression, OCD, panic disorder and high anxiety disorder) caused from an imbalance from having children, and I tend to find, when I'm feeling at my lowest times, it's when I stay away from the internet. I don't want to as fandom is my escape, but I end out not even posting in my journal as I don't want to have to explain things being related to my illness because I feel people will just think I'm whining and using it as some sort of excuse.
Having said that, I know I can post in my journal if I wish to really, as my flist are a good bunch.
But I agree, as a mental illness sufferer, fandom is not the most welcoming of places at times. It's like you're allowed to have it providing you act like you don't. It pretty much reflects attitudes I find in RL with my family.
Sorry if I've gone on a bit, it's an issue that's pretty close to home.