Even with server core, the system requirements (especially storage) of getting a Windows box off the ground are much higher than a Linux machine. Plus, licenses for the OS and SQL server can become very costly. And don't get me started on the Brobdingnagian Microsoft licensing model, designed to inflate cost and employ "licensing specialists."
I mean, I'm fine if the frontend developers go running for the hills if they are forced to contemplate the idea of not using .NET, but does everything really have to run the Microsoft OS/DB stack? I appreciate that VBRs can run on Linux. Let's get that extended to other parts of the stack as well.
Unless otherwise specified, I am asking about something pertaining to Linux. We use Windows as infrequently as possible, and enthusiastically seek ways to reduce that usage further.