Lots of stuff like this already exists and has been proven useless. A guy here on lemmy was a big answer type on some tech support sub. He used one of the account scrubbers to nuke his account before he deleted. Went to look again a few weeks later and all his top comment answers had been restored.

They haven’t bothered with most people because they simply aren’t useful to making the place look attractive but no mater what you do your comments are stored and will be sold off to the AI companies.