First, every company uses Windows, you can’t avoid this and you’ll have to learn how to use all the tools (Visual Studio, Office365, everything else). Yes it sucks, no you can’t use another OS if you want to eat.
As for why .NET and C#: my shitty theory is that companies used to write software in C++. Then Java came along but it was not evolving fast enough, and Oracle was suing the whole planet. Microsoft invented C# to annoy everyone (both C++ and Java) and it worked because C# is actually a good language. You have a big SDK, you can do everything that Java does, it’s easier than C++, and you can use your C++ code with C++/CLI. C# was a good alternative and people used it.
Do you think enterprises will make a turn in this attitude?
C++ is too hard (I know, I use it daily), and Java is dead. I don’t think companies who use C# will go back to using an older language. That would be suicidal.
Not Gandi. They were very reliable since the beginning of the internet but they sold the company and went downhill since.