I'm sure that most often it's to prop up self-control, when "the spirit is willing but the flesh is weak" so to speak. I remember two cases that were different though:-
i) someone applied for a job that involved "vetting" like they might do for the military, and this person wanted to delete everything to do with MB
ii) what I consider sadder, and more sinister, was a person who was worried about their parents and/or church discovering their online self.
Not saying that any of the above apply to Cuthbert. My guess is that in his case it's out of remorse and self-loathing after posting anti-Biden propaganda
(That's a joke, Cuthbert, if you are still lurking. I'm sorry you have left us, and I won't forget the chats we've had over the years: especially your invention of an Architecture Thread, for which I am very grateful.)