Valid point. I guess I was thinking the HPC systems. Certainly every client-facing terminal is a Windows box. I don't know much about the network stack, but there's clearly a lot of Windows there too.
We're an external partner pulling data via a 24/7 Windows-based web service, a system of record. The three we work with are all Windows, but three is likely a blip in their system count.
All I know is it's weird how they and their vendors manage the systems and environments. Glad it isn't me!