Yeah - Excel and other 'productivity' apps are probably still the killer apps for PCs, especially for businesses. I assume businesses still drive the majority of PC purchases.

Some other factoids:

There are >1B PC gamers (source: random articles on the web). I'm guessing the number of mobile gamers is 2-3B.

There aren't that many active Excel users. Even Google sheets (free) has only a few hundred million users.

Most web browsing is now done on mobile. The transition happened sometime ~2015 for most of the world and something like 2017 for 'developer markets'.