It's politics. A while ago I interviewed for a back end dev position at this "big" company and they wanted to give me an offer at which point I made some requirements such as couple of decent monitors and Ubuntu (WSL wasn't yet out then, but I wouldn't have considered it anyway). They said no, because they were constrained by their "IT department" which wanted to install all kinds of shitty spyware as I understood. They also admitted that they lost other good developers who made similar demands like working on Macs and such. Needless to say I too declined their offer, because I'm not interested in companies with developer-hostile policies.
In UK many true consultants use their own hardware, in fact it is basically mandated by law (IR35). I have a state of the art Dell Precision 7750 running Ubuntu on it and I wouldn't ever consider a company who tried forcing me into Windows.
Should honestly stop working for companies that force Winblows. Might as well move rocks from one pile and back, because those jobs have little to no purpose than wasting your time when you could be doing important things with your life.
I don't come into contact with Windows much, but had an ~18 month contract a few years ago. A Fortune 500 company, an interesting project. I ended up writing some important parts in software that has an actual positive real-world impact. During my work, I was of course given a Windows machine. I installed Cygwin and did the vast majority of work there. I'd drop back into Windows proper just for Outlook and to occasionally use an industry-specific tool.
Sure I would have preferred to work on a Linux machine, but having to use Windows doesn't mean that the work is pointless, or that I cannot put my best effort into it.
So you used Cygwin to do the work why? Is it because it was actually easier to make progress when it came to actual work (not just needing to use the corporate tools to communicate with coworkers or track your time)? From the sounds of it, Windows actually hindered you so you tried to find a way to use Linux tools so that you could make the most positive impact. That is exactly what I'm saying.. why make concessions and limit yourself.