The only things these things teach me is that "Platinum - It runs perfectly" is that ProtonDB creators clearly have a different view on perfect. "Doom Eternal runs perfectly - it just have some pink flickering every minute!" "runs perfectly - it just closes when you try to start it." "runs perfectly - multiplayer doesn't work though." Microsoft can change DirectX whenever they want, that goalpost is always going to c…
I share your criticism, but just "Create a standard" is maybe a bit hard to do. Game devs need a market. The linux market is not really the biggest one, neither in numbers, nor in money. It only became a bit relevant, because Valve used linux, to threaten Microsoft, as they tried to get a big cut of game sales, with their own market. So good for linux, yes, but the normal linux game market is still quite uninterestin…
I know of at least one game that's regularly in the Steam top 10 (Path of Exile) that is doing a port from DirectX to such a standard, Vulkan.
Not to support Linux, but because Vulkan is cross-platform, allowing them to reuse their code base for a mobile game, and also to be able to potentially support things such as Stadia. They also said this will lead to a mac port and may lead to a Linux port.
So there might actually be incentives already for game devs to use cross-platform tech, which could lower the barrier for Linux ports significantly and make it worthwile.