When people gather and complain, it might be that each new posting is simply venting. There is a sense that if others can complain, so can I. But I believe it is much deeper for autistic individuals.
How can you not be depressed at time when social connections are difficult? How can you not wonder what it is like to understand vocal tones and facial expressions without having to memorize pages from books on body language? How can you not feel isolated when so many people avoid you?
Put simply, when your social skills are the ones most affected by your disability, it is only logical that you will suffer some periods of depression related to the isolation we experience. Everyone feels like an outsider sometimes, but imagine being an outside all the time. Every relationship suffers, even those connections that are most important to you.
I do not like therapists, though I would listen to a psychiatrist (an M.D.) before I would a clinical psychologist. I consider depression, like autism, a medical condition; you might need medication and you might not. You definitely need a doctor who can prescribe something if you are at genuine risk of hurting yourself or others. Talking when you are right at the edge isn't always enough.
As I wrote in a previous posting, I think we need to separate "real" medical conditions from normal emotions and experiences. Being depressed after a family member has died is normal. Being unable to go to work or school for two weeks is not normal. Crying every night is not normal, but crying after a single bad day might not be clinical depression. You need to be careful to recognize what is likely normal from the abnormal.
When emotions are already overwhelming, I suppose it is easy to slip into a state of inactivity. When things that upset you lead to screaming, a bad mood is extreme no matter what other people try to tell you. I know what it is like to be upset for days over a single incident, but I also know that it isn't clinical depression.
What worries me is that depression might always be a single event away. Think about how cyclical that could get.
Reading negative blogs and visiting online chat rooms populated by depressed individuals is not a good idea when you are already upset. The irony is, online is the only place some of us feel connected to the world. I wish I knew how to break free and avoid the paradox completely.