Personally I'm surprised this debate is happening at all. By the numbers I'm seeing, the desktop is in decline. How you expand in a declining market is something that profoundly evades me.
Some random nitpicking:
- The fact that some 3rd party vendors have success selling alternative development environments to iOS and/or Android doesn't mean that the original tools were necessarily lacking. The fact that Microsoft provides a rich set of tools for developing in Windows (VisualStudio and co) hasn't stopped other vendors from selling such tools too.
- Businesses like to not have to train their employees to use their systems. Said employees are/have already using/used Windows and are accustomed to it (that is true EVEN if MS changes the UI every so often.) No value-add for a business to switch to Linux on the client side.
The only question is whether the Linux desktop can help someone somewhere make more money, lots of it. Android had a good story for that. The Linux desktop not so much. Until that's resolved, and I posit that it can't because the desktop world is declining, then we're not going anywhere.