I'm not sure how they could have failed that if that was never their goal in the first place. The entire point of Proton is that the Win32 API is infinitely more stable and worthwhile to target than anything Linux distros offer, and that the financial incentives aren't there for developers to 5x their platform distribution effort to reach 1% more users. An approach that relies on developers doing that would never work, and fortunately for Valve that isn't their approach.

What's the purpose of a native build if the windows build runs just as good, or even better?

They ensured that the devs need not worry about another build target that requires extensive QA. Maybe in the distant future we will get ubiquitous native builds, but honestly and again, who cares?

Proton and Wine means there is a single target now, instead of the fragmented mess that is Desktop Linux today.

Tbh, why bother?

kernel32+user32+gdi32+d3d[11|12]+dxgi is a pretty great API abstraction for game development. And unlike Linux desktop APIs the Win32 APIs are actually stable, so those games will also work in 5 years, and most importantly, performance is the same or better than on Windows. It's unlikely that game devs directly targeting Vulkan would do any better, and when using a high level engine, any layering overhead in Proton is negligible anyway. And don't even get me started about the state of audio APIs on Linux ;)

Also don't underestimate the amount of workarounds and tweaks that (most likely) go into Proton for games that make poor system API use. Without Proton those game-specific hacks would need to go into MESA, Wayland, X11 or various system audio libraries. At least Proton is one central place to accumulate all the game-specific warts in some dusty corner of their code base.

TL;DR: just think of Proton as an extremely low level and slim cross-platform API for games (not all that different than SDL), and suddenly it makes a lot of sense. And I bet that in 5..10 years Windows will have regressed so much that it might actually be better to run games through a Proton-like shim even on Windows (assuming Windows hasn't become 'yet another Linux distro' by then anyway) ;)

> As long as they depend on Proton, they haven't fully solved their problem.

Maybe not, but they fully solved my problem with games, which was that I could not play on Linux. I started playing again just because of the SteamDeck, I think it's a pretty big achievement :-).