I wonder if SteamDeck counts toward desktop share here? It kinda is a desktop OS, even though it's mainly used on a handheld device. Either way, I think that contributes a lot to normalization and stability of the ecosystem, if not device count.

The big factor though is probably just a shrinking market. For people that aren't computer nerds or businesses, it's getting less likely they own a laptop or desktop, and more likely they think their phone is good enough.