It backs up to the Microsoft Account
Still, some people create an @outlook.com email, set up no recovery options, forget the password, and find themselves locked out.
If you’re doing things properly, you’ll know your Microsoft account password or have it in a password manager (and maybe have other account recovery options available like getting a password reset email etc.), and have a separate password for the PC you’re locked out of, which would be the thing you’d forgotten. If someone isn’t computer-literate, it’s totally plausible that they’d forget both passwords, have no password manager, and not have set up a recovery email address, and they’d lose all their data if they couldn’t get into their machine.
Even if you have your Microsoft account password, it doesn’t help when you can’t even boot into Windows.
Microsoft fucked that up in the Home edition, where the key in your account won’t work.
Timestamp 8:48 in this video
https://youtu.be/pIRNpDvGF4w