You are right, and yes, they could run Windows, but it’d be pretty silly.

All the applications they run were written with a pure POSIX mindset, the jobs are run headless, and the legacy of much of the application code dates back to before even Windows NT was a thing.

In the late 2000s, Microsoft actually made a concerted push to try to get into the market, and it was just a laughable failure (they brought nothing to the table, had reduced ecosystem compatibility, and tried to charge more all in the process.