That is the point. They stop you from memorizing it “just in case” and reusing it, and they force you to use a password manager.

For the average user, which doesn’t use a password manager, this is great. It means they can’t get phished. And it’s also great for the average password manager user, who keeps dozens of insecure and reused passwords in their vault because they manually thought of a password when signing up instead of randomly generating one.

If you’re already using a password manager and random passwords, the UX is designed to be the same. It’s just a way to get regular people to do this.