Welcome to 2014 where cross-platform means "Ubuntu, CentOS and Mac OS X".
On the flip side, while I am more than happy to deploy new development projects to Linux hosts, and even in docker containers, I'm still stuck developing under windows, and having to run a VM to do most of my development isn't something I'm all that in favor of.
That said, Azure is about the only cloud provider that really caters to .Net deployments, that is correct and probably accounts for a lot of it.
Me employer's next generation of applications is being deployed in Linux on Azure, because of their better support for our legacy applications (some will be around for quite a while)... which is part of why I said that "yes" running in windows is important.
If Node and Mongo didn't run in windows three years ago, we wouldn't be migrating to Linux today. I introduced Node in order to improve client-side web resources in a few web projects... once that was in place, it was a natural fit for one-off scripts (importers, timed tasks, etc). From there it became the API service for search (with mongodb behind IIS/ARR). Because of that, and the stability so far, it's our next generation platform. None of that would have happened without being able to run on windows.
I think a lot of people/companies have some of these. Even if you're 90% Linux for example, and 10% Windows, its nice to have a tool that works across the board.
Since this also seems to be targeted at laptops however, I bet Windows is still a large percentage there!
What I meant is that they don't even say 'works on Linux' like in 'they don't even cover all the most commonly deployed Linux distros'.
The idea that they should test on every distro in order to say that it works on Linux is a bit silly.