Sure. But it's on by default, isn't it? Just like Apple's upload is on by default.

Also, chromebooks require such a sign-in as well, and I'll bet they enable that syncing by default as well.

Singling out Apple here is kinda silly when they're encrypted (if you don't trust Apple to tell the truth there, running their OS at all is risky), and when the behavior is that which we'd expect.

And at the end of the day, using Apple's password manager is mostly (exceptions including wifi passwords) optional.