Proton is a wrapped/enhanced version of Wine, which has been a thing forever. A large chunk of the Steam library worked perfectly fine on Linux before Proton.
>A large chunk of the Steam library worked perfectly fine on Linux before Proton.
Source? My recollection was that it didn't. Wine had awful direct x translation, I'm not sure if it could do dx11 at all when the steam machine came out. DXVK is a proton project and without it few games could actually run at all.
That's not fair. Vulkan didn't exist when the original Steam Machines launched. Wine's Direct3D implementation also had different goals than the DXVK project, such as supporting macOS, older hardware, and non-gaming DirectX uses.
... for modest values of "fine". Compatibility, stability and performance have improved immensely the last couple of years, for a large part thanks to Valve!
Yeah, WINE may have been around forever but its development was massively accelerated by Valve dumping truckloads of money on CodeWeavers to have them work on fixing games full-time. Plus neither of the two most popular anti-cheat solutions worked in WINE at all until Valve lobbied them to support it.