I don't think developers should take the blame for not using a language which has from day one been a deliberate trap intended, by its very usefulness on Windows, to tempt people away from Java into creating programs which can't survive outside Windows. It began as an attempt to nobble Java with incompatibilities (Microsoft J++), and when that got sued off the market, it returned as a "different language" (C#) that looked nearly the same, trying to play on all the same strengths - except the ability to escape from Microsoft's OS. Nor has that ever ended. Microsoft has no interest in helping Mono reach parity with its own version.
You can use it, but your programs will be stuck on Windows, and your time and effort and dedicated mental resources will be joined at the hip to Windows, in a way that doesn't apply to almost any other language.
I can't blame you for not being up to date with developments on .NET platform or in the Microsoft world - but please o please refrain from making comments about the issue you are not informed about and obviously haven't looked in to for the last couple of years.
Microsoft has their own cross platform open source .NET implementation under MIT license supported officially on Linux and OSX. https://github.com/dotnet/coreclr
Not only that but they are opensourcing and porting huge parts of their stack like build system, web framework, etc. and are supporting it officially on Azure cloud. https://github.com/aspnet/Mvc
They are doing pure OSS from scratch projects such as LLILC - a static compiler for CoreCLR based on LLVM : https://github.com/dotnet/llilc
Further more even before that Microsoft has started opensourcing large parts of their implementation at the request from Mono team and Mono has taken those + CoreCLR and made their implementation better - showing that they actually wanted to help Mono team implement feature parity.
And finally Microsoft recently acquired the Mono team (Xamarin) and will probably fold that in to their OSS offerings.
So please stop the FUD - it's not helping anything - I realize you have an opinion but before voicing it please check if it matches the facts - otherwise you're just creating noise in the discussion.
So microsoft has done all this in the past few years. Yes, they are turning their reputation around. But Java has had this from the start, so has a 20 year head start.
Microsoft is forcing android vendors over patents for things they didn't even invent. Imagine what they would do if people used things they did actually invent.
They are giving patent exceptions to their OSS stuff (either explicit in coreclr or inlicense trough apache 2 in mvc for eg.)
So again please cut the FUD and try to get informed before discussing thease things - you could literraly find the stuff I'm talking about in a google search or two
You can use it, but your programs will be stuck on Windows, and your time and effort and dedicated mental resources will be joined at the hip to Windows, in a way that doesn't apply to almost any other language.