Question Author
"Surely, if anyone wishes to exclude themselves from AB then all they have to do is to refrain from posting into its columns."
That's not enough for some people. The page makes it quite clear exactly what gets kept and what goes.
It removes all subscriptions, including the newsletter - so that might be a reason to do it. Save you unsubscribing from each when you want to leave.
"Could you look into the option of not allowing people to select their own answers as best answer?"
Yes. We're planning that for the following upgrade. For the moment we could add a derogatory badge for such swines?