I know many users will be "Oh shut up, you just don't want to accept it", but there's a bit of a valid argument here. In a ways, it's kind of discriminatory where if you wanted to make things easier for your user by adding a single sign on kind of solution like FB/Twitter/Google, you must add Apple, or you're stuck with regular ol' username/password. Otherwise you're booted from the service. "Other services are optional, but we're mandatory". It's kind of like saying "If you want to use your Visa or MasterCard here, you're required to have a store credit card too, even though you might not use it. Otherwise, just accept cash."
It's stripping away the liberty of the developers to add services without adding a native service so that they're always there. I personally like SIWA and use it, but it kinda sucks that it's such a heavy requirement for a sign in feature. I know I'll get flack from users (heck, Apple users are already becoming a little skeptical of 3rd party developers), but to quote Marilyn Manson "something beautiful, or something free".
Im actually all for SIWA and use it when I can but on the surface it does seem like a clear class of tied selling. I mean something similar got MS in trouble in the 90s... forcing IE with Windows.
Im curious does anyone know if Google requires Sign-In with Google in Android Apps if you use Sign-in with Twitter or Facebook? Is Apple the only maker that forces developers to bundle its sign-in option if you use a competing option?
Is sign-in with apple offered on android at all. I think it is on websites - but maybe only via Safari...