> is pretty meaningless because the default install doesn't really do anything

Which is a good thing. An important thing. The reason you're stuck in a perpetual update cycle for most Linux distros and for Windows is that they ship with an insane number of things that most users have no need for. Yeah, every laptop definitely needs NetBIOS and iSCSI and UPnP turned on by default.

It's true that everything you add on top of the OpenBSD baseline increases your attack surface, but it's a saner approach than shipping with a gigantic attack surface and then forcing you to know about and disable the things you don't need.

> Classified workstations in National Security contexts? They run Windows.

Which is almost certainly a combination of the complexities of govt IT procurement, the needs of non-technical users who may only be familiar with Windows & MS Office, and the enterprise management features of Windows that aren't as good in most other OSes.