Ask HN: What's preventing you from using .NET?

I had the chance to do research on C#, F#, .NET (I must admit, I'm still confused with all the various names and versions), and ASP.NET (core?). I genuinely find the technology stack intriguing and am considering using it in a few side projects. If things progress well, I might propose it to my employer. What factors are hindering your adoption of .NET? Is it because of the Microsoft label? concerns about the desktop GUI support? License? Could it be related to tooling, or are software requirements and packaging considerations playing a role? or something else?