I disagree with the argument that changing Linux to dominate the desktop would kill what we like about it. Pick a distribution - Ubuntu, OpenSUSE, Manjaro, Mint, Elementary, Solus, Knoppix, whatever. Assume that enough features, polish, and in-demand commercial applications are added to it that it takes off like wildfire. Eventually it dominates some crazy percentage of the desktop market, like 10%.
The wildly popular distribution will probably be locked down in terms of features and options so the non-tinkerer has a hard time shooting themselves in the foot. So just about anyone that listens to Bad Voltage won't want it.
But we still get the benefit of new applications targeted for Linux, right? So even if I'm still running Debian on a desktop and don't give a hoot that fifty million people use OpenSuse every day, there will be video cards, wireless cards, Steam games, non-Steam games, and applications like Photoshop that I can only run easily on Debian precisely because fifty million people run OpenSuse.
Right? Wildly popular desktop Linux is only bad if it becomes like Android - an open source kernel with so many proprietary device drivers, boot loaders, and proprietary services built on it that it's open source in name only.