There are a few forces at work here: .Net begets Windows: long-standing MS strategy has been to provide tools & resources that drive Windows adoption. The mil

There are a few forces at work here: .Net begets Windows: long-standing MS strategy has been to provide tools & resources that drive Windows adoption. The millions problem: MS measures licenses for things in the millions. Anything below that is really difficult to make a business case worthy of pursuing (in their world.) Are there millions (plural) of potential adoptions for .Net on non-MS platforms? How do they make money: .Net is essentially a loss-leader for them now, as they don't charge for it (they make it up in OS licensing.) They're not in position to derive revenue from other platforms. Target audience: while Linux is the dominant OS in most startups, Windows heavily targeted to corporate environments. While spending resources to target other OSes works for some people, some users who have large Windows installations want to see resources directed at pushing their platform. And, those users are ones with license dollars behind them. *The koolaid factor: if you've spent time in Redmond, you get this weird feeling there's a large contingency of people who have no idea there's a different OS out in the world. Seriously, in some places over there it's like the Truman Show. These aren't my talking points; I have friends & colleagues in/around MS who frame this for me. I don't advocate these positions, only that they are significant issues in the conversation.