You've hit the nail on the head. That's why I strongly preferred email and password login, backed by a keepass(xc) store to hold the data. Owned by me, backed up, impossible to take from me, the works. Sure, most of the time I have to verify my mail address, but after that the account is mine. Well, okay. On some services, I have to "confirm the new device" I'm loggin in from, so I still need access to my mail.

Weeeell... Some services I use seem to have switched to a magic link EVERY TIME for login. No password anymore at all. And all of a sudden, my mail account is the single point of compromise for these accounts.

And there is absolutely nothing that I can do. If the mail is hosted by someone else, they may terminate my account at a whim. Or give it to someone else who happens to have convinced my phone provider to hand them a sim card with my number on it. If I do self host I still need a domain, and I can never really own a domain, only rent it from somewhere. So, whenever that lease goes up, my account is compromised by default.

I really hate that this problem seems still unsolvable. Keybase had the right idea, but no one used it and they got aquihired by zoom during the pandemic...