Then don't keep it ?

We're talking about chat.. you shouldn't be logging the contents, at most a bit of metadata to prevent abuse (eg. a connection log to identify and block spammers).

If you don't store that metadata longer than needed (a couple of weeks? storing it for years would be hard to defend) you have legitimate reasons to keep it, and don't need to worry about deletion requests

That's why I mentioned I'm ok with projects reacting strongly and removing themselves. Removing my info (and many other GDPR points) is in my interest. If they can't do this, I'm glad I won't be their immortal user.

Smartest, most paid profession in the world and now bunch of those people are incapable of running DELETE SQL queries?

You can just do it manually... I have a feeling deletion requests will be pretty few and far between anyway.

Why?