Lots of dev go out of their way to make sure their games play nice on Steam Deck.
The alternative is that they do not do this at all because it is too much work for too little payoff. Proton is driving real Linux adoption in PC gaming.
Really? Name a AAA game studio that actually activily does anything instead of letting Valve do the work themselves, coming up on their developer blog "We did this for Proton".
Proton is driving the adoption of PC Windows games on Linux.
The alternative is that they do not do this at all because it is too much work for too little payoff. Proton is driving real Linux adoption in PC gaming.