AIBU is robust, and yes does have blunt comments, but no one has to read threads on it.
Yeah ok....except that every week I see people who post in AIBU "for traffic" and who treat AIBU as if it is Mumsnet in its entirety. So there is that too - it's not that I disagree, but I think many people come here first or often in their Mumsnet browsing journey.
But I also think this is a bit of a specious argument. So many people over the years have tried to portray AIBU as some sort of arena of battle, and if you don't like the heat, get out of the proverbial kitchen.
Does it have to be that way?
You originally wrote "Other forms of entertainment are available" before editing your post @TeenToTwenties and I think you'd struck on the heart of the matter originally.
That AIBU has become entertainment to people. They want to see an OP torn down, made to feel silly etc.
So certain posters feel emboldened to get in first on a thread and give the person's "head a wobble" as soon as they can.
I hate it personally - I think you can do so much more for a person by just showing them where they could have faulty thinking, rather than saying "You sound delightful" or "You sound awful to live with" etc.