I keep seeing disclaimers on AIBU threads, saying 'Oh but of course I can say that and be really horrible to the OP because this is in AIBU'.
I think it's being taken as the point of the board - to vent your own frustrations even if they are nothing to do with the thread...just a place to go and be mean to someone if you have had a bad day or don't like people with 'mummy' in their posting name, or who wear white socks, or so on.
I really hate it and wish it wasn't there. Surely it's supposed to be for those who really can't figure out a situation, or in order to have a wee joke sometimes, a silly vent about something daft, I dunno...not a place to kick each other around.