I remember when I was younger Apple had computers everywhere. If I went somewhere there was a very good chance their stuff was being used. Schools, libraries, offices, etc. Now I nearly never see their computers in these places. Sure, more people may have them in their homes, but I would be surprised if the percentage has not actually gone down.
Back to the point, I don't think Apple's sales has much, if anything, to do with the rise of Linux gaming. I don't see a massive increase in gaming support for other operating systems...is Apple to blame for this, too? I think the growth of Linux alone is the reason for the increase in Linux gaming, not something that has nothing to do with Linux.
I miss the Apple of my early years, but cannot stand the company as it has been for a very long time.
With the help of Linux, we've moved beyond the Apple/Microsoft paradigm - our computing lives now are mobile and largely platform agnostic - also, Apple's software platforms have everything to do with Linux.
Apple's devices are the popular face of Unix, like it or not. Hundreds of millions of Macs and almost 1 billion iOS devices have been sold within the past decade.
All I am saying is that the OS X software market has become huge for developers (not Windows huge, but huge). By many metrics, iOS has become even more lucrative than Windows. Developers support Apple platforms because there is money in it - and once they are multiplatform and up and running in a *nix environment, Linux is relatively easy for them to support.
Linux stands on its own merits, and I'm not trying to attribute the success of Linux gaming to entirely to Apple, but it's definitely part of the formula.