Why not?

It is already there, has enough choice to keep me entertained, I don't suffer from FOMO.

I try to avoid vendor lock-in when I can.

I'm a Windows user. I don't want to lose my apps if (really, when) I eventually switch to Linux.

Buying my games on Steam means I can play my games anywhere.

Not really, because not every game on Steam does exist in all other platforms supported by Steam, and Proton is still Windows anyway.