Maybe because there is a large backlog of old games that will never be ported to Linux? Have you considered that game developers and not valve are responsible for providing a Linux port of their game and so far have managed to do a worse job than a DirectX implementation for Linux?
The collective time spent on developing proton is probably less than a dozen high profile Linux ports.
The latest commit to proton 9.0 is three weeks ago. The latest commit to an experimental branch is 3 days ago and it is just an update of a wine version and no other commits. A lot of proton commits just update a version here and there.
The focus is certainly not on proton. It is simply very cheap to work on it, because it is highly effective. The steam deck probably cost them more software and hardware developer hours than proton.
The collective time spent on developing proton is probably less than a dozen high profile Linux ports.
The latest commit to proton 9.0 is three weeks ago. The latest commit to an experimental branch is 3 days ago and it is just an update of a wine version and no other commits. A lot of proton commits just update a version here and there.
The focus is certainly not on proton. It is simply very cheap to work on it, because it is highly effective. The steam deck probably cost them more software and hardware developer hours than proton.