Yeah I thought this was a weird take too. Too often people take privacy for "I can do what I like". IMO deleting something you've sent to someone else is not a privacy concern at all.
Can't remember what the algorithm is called.
I don't know if it actually could work in practice:
The right-to-be-forgotten advocates argue that everyone should have the right to demand that any trace of their previous online existence be deleted. On social media of course, but also independent web forums, chat logs, git commits, etc.