One valid reason might be someone is in trouble in regressive oppressive regimes like one in Iran. Normally if they are arrested in a protest people report their account or they ask relatives or friends to destroy the account on social media to not give obvious extra evidence to the government.

Because of you've forgotten to put the attachement in… Or Even worse: did post something terribly wrong/ a fakenews … you'd be better able to correct/ delete false Information!

I mean by that when I post something by mistake or post something and then regret it and want to delete it, that freedom should be