You have a point, although I have come across C# run on Unix often. My response was however for a language to learn OO principles. Some years ago many of the UK universities used to teach Smalltalk to show these principles although you don't see the job boards littered with vacancies for Smalltalk developers :)
Nowadays they have mostly moved to Java thank goodness so people leaving universities have more of a chance of getting a real job.

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Joe