I don’t understand how this point keeps getting raised. It’s no different from making an account on ANY platform. Sure, you can choose an instance, but if you’re already browsing then the “create account” (or whatever it says) link takes you to a registration page just like any other.
Hotmail was owned by Microsoft when I signed up in the late 90s. It’s no surprise it’s still around. It hasn’t been my primary email for a long time, but I still use it as my MS account. So really it’s just my Minecraft account.