

They want to make money off of services, every service they offer requires a Microsoft account to purchase and use. Everyone that they force to make an account during setup is one step closer to paying for a Microsoft service.
There are obviously tradeoffs (less sales of these versions of windows and some users pushed away from Windows altogether among others), but the motivation is clear.
poweroff
orshutdown
will work on almost every distro. Even systemd ones (they are usually symlinks but doesn’t really matter because they work).