You might be misunderstanding what the poster was talking about -- it's not that you'll need an Apple ID to sign up for a site, it's that once you sign up with an Apple ID, you might not have a way to link your account to a different email address. That effectively means that you'd need to recreate your account when you move away from Apple.
Of course, the other side of that is that sites are probably going to have ways to link accounts, and it likely won't be a huge deal. They certainly have no motivation to help Apple with lock in. It's not going to be any different from the process that exists today for moving associating an email with an account you created through Google/Github signin.
Still, it would be nice to have a way to use this without an iPhone, or it will be a (small) extra piece of friction you just have to deal before moving ecosystems, rather than piecemeal after getting a new phone.
Also note that the same exact concerns exist with Google/Facebook sign in, it's just that they aren't tied to a physical device so you only need to worry about losing them if you're making a conscious decision to delete your account.
Of course, the other side of that is that sites are probably going to have ways to link accounts, and it likely won't be a huge deal. They certainly have no motivation to help Apple with lock in. It's not going to be any different from the process that exists today for moving associating an email with an account you created through Google/Github signin.
Still, it would be nice to have a way to use this without an iPhone, or it will be a (small) extra piece of friction you just have to deal before moving ecosystems, rather than piecemeal after getting a new phone.
Also note that the same exact concerns exist with Google/Facebook sign in, it's just that they aren't tied to a physical device so you only need to worry about losing them if you're making a conscious decision to delete your account.