It's a great anecdotal article. If you looked at the entire industry, I think you'd find mobile had a larger share, but that it still would be dwarfed by PC.
There's also the price expectations issue. Mobile gamers only expect to spend a couple of dollars on games, while PC gamers willingly shell out $10-20 for a solid title. PC games might also sell better b/c getting on Steam or GoG is more difficult than getting into the app store, so there are fewer to choose from.