I'm not a developer in this situation, I'm a user. There's no contradiction. Apple makes my user experience better by forcing app developers to play by their rules.
200 years before it could be, "Slavery makes my life experience better by forcing slaves to play by the rules and serve me".
Your position is immoral. Coercion of any kind is bad. Approving it for egoistic reasons is equally bad.
You could freely support apps that do use Apple sign in voluntarily, but you like it that the developers are forced to provide it. Immoral and pathetic.
I don't believe in treating users like they're dumb.
There's a "keep me signed in" feature too. Or if this is a serious source of confusion, use local device storage to keep track.
In practice I don't consider anything for each app. If it's worked I used gsuite. If it's personal I used Apple. OAuth is the new "same password used everywhere" but now we click logos.
The difference is that Apple's sign in is beneficial for non-technically savvy users, as it both allows using an anonymous email alias and alleviates the need for password creation. Those are both reasonable privacy and security trade-offs for a tiny bit of (generally reversible) ecosystem lock-in.
Tiny bit? Try and migrate dozens of app accounts to a non-Apple email, as a non-technical user. Disregarding the sheer amount of work, such users won't even know how to send emails from the private addresses they signed up with, making it hard for app developers to identify them. It's always about control and lock-in with Apple.
To add to the other threads, Apple Sign-in is only required if you use any other sign-in providers (Google, Facebook, etc.). Since Apple Sign-In allows anonymous signup, I like this rule (remember back then when Tinder forced you to use Facebook Sign-In?).
