Developement is not an easy task and for a small team of indie dev, it's impossible to port their games on multiple platforms. They don't have the ressources nor the time to test and patch multiple versions because each platform is a source of bug. Wine is a great tool to minimize this effort. You can't ask a game dev to port their game only on Linux. It's inconceivable at the moment. As a developer myself I understande those limits and I think Proton is one of the best thing that happened for Linux gaming and for Linux adoption. It's only my opinion on the subject but I'm here only because it would be cool to be able to play more games directly on itch.io. I love gaming, I love Linux and beying able to play my favorite games on Linux is the best.