Even if that's the case, that still supports my original point that Microsoft having 90% of the desktop PC market has become increasingly meaningless in the age of web and then mobile. In the grand scheme of things, few new software initiatives are targeting Windows compared to web and mobile and only a select few companies are making any real money writing desktop software.

The example given of Autodesk kind of proves my point. They have the same annual revenue making CAD software that King digital has making Candy Crush.

Games aren't tightly tied to a single mobile platform now - most of them use a cross platform game engine. The reason they won't go to the web is payments are frictionless on mobile and you don't have to trust anyone but the platform provider.

Today anyone can setup their own shopping site and probably manage their own shipping but most small merchants still sell on Amazon.

I mean, I agree with your argument -- I'm just extending it to say that no platform dominance matters in the era of the web. Any software with mass-market appeal is going to be web-based so that it can reach the largest possible audience.