Yes, I think developer reluctance to engage with desktop Linux is because they want to have a single responsible party to work with, and that is not really possible. I suspect that in many cases, market size only plays a role in evaluating support costs.

Whatever one thinks of Valve and Google, they are both, in their way, helping to make Linux gaming a more viable proposition, which is a good thing that I hope will continue. It will also be interesting to see how big developers approach Apple support once they move to ARM.