Can someone with Windows Server experience please explain how this might make any sense at all?

I've never uses Windows Server or any of the MS server technologies. The closest I've gotten to this was using Exchange in the context of being just another user in a corporate environment.

If you need Windows Server, why would you want any part of Linux?

And, if you need Linux server, why would you pile gigabytes (?) of MS Server code onto your server?

I can see (and I like) the utility of WSL on the desktop for development. As this evolves it will become more and more useful. But on the server? Not sure I see the point.