> All logins are now busted. Some percentage of users is lost forever because they can't remember their login credentials and instead of going through the recovery flow, they go use Bluesky.

That includes everyone who had 2FA active before Musk made that a "premium" feature and subsequentially lost their 2FA device. What a clusterfuck, that one.

> Every business integration needs to be updated. Google App Store, Apple App Store, Amazon Appstore... They all have bindings to twitter.com, and some part of their flow will panic and flag a security issue if they see it's turned into a redirect to elsewhere.

And that's assuming the integrations even support changing the primary domain name in their OAuth backend, which a lot of them will not. Or you have appliances that got made years ago when Twitter integration was the fad of the day - I 'member there's a fridge out there that showed tweets on its screen -, game consoles or other devices that don't get firmware updates any more.