You could make the same argument about C, which exists on much more platforms than C#. But writing in C does not make a program portable. Neither does writing

You could make the same argument about C, which exists on much more platforms than C#. But writing in C does not make a program portable. Neither does writing it in C#. So yes, C# compiler might be portable, but programs written in C# are not. So yes, C# compiler might be portable, but C# programs are not.