Kinda related: back on Windows 7 I did add my MS account to Credentials Manager out of pure curiosity. But there was nothing else that could be done beside storing login and password. Even Windows Live applications bundle hold login data separately from Manager.

So I removed that account but when W10 was released, it was offered during initial setup of upgraded system. Windows still stored information about that account somewhere.

And yes, there are system tools still present today in W11 that allows users to create additional local accounts beside the default one set during installation - that's mmc snap-in (terrible name) local users and groups or net user for console. But I totally get it and support: people don't want to be forced for an online account out of the box, for a local workflow.