Attacking someone for who they are, or worse yet, telling them that they aren't who they say they are, is extremely inappropriate in a support group. If you do these things, you are likely to make quite a few enemies, beyond the people that you attack directly, and you are likely to be introduced to several people's killfiles. If you must say something harsh in public, the mature follow-up is to drop the subject and let it go. All too often, that's not what happens, and the entire newsgroup becomes consumed in a vicious fight that may last anywhere from days to months. If you are considered the instigator of a flame war, your name will live in infamy in the newsgroup.
Many people post anonymously.
Flaming through some anonymous servers can cost you your anon account. Flaming from a forged address guarantees instant, complete, and lasting loss of credibility. The worst part about flame wars is that they are extremely repititious. Whatever the subject is, it's happened before, and no one really wants to be dragged through it again. But they still happen.