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.
