So, at least from personal experience yes, it makes absolutely no sense to port to Linux, if the result is still worse than proton.
Regularly test under proton during development, and you got a Linux Version of your game for free. From my experience, epic already took good care to make sure unreal engine works well under proton, so if you just pick that and don't add a ton of additional stuff that uses esoteric winapi stuff, you're already set.
We all know how that ended.
Another comparison that I think is more apt: "IBM PC Compatibles run IBM PC software better"
(In that sense, developers (or Linux porting studios) switching from their in-house compatibility layers to Proton isn't really a change in terms of those ports being 'truly native' or whatever.)
I wonder if what we're starting to see, rather than the inferiority of source ports, is actually that some of these alternative compatibility layers are just no longer keeping up with Proton, since Proton/WINE has such wide use/testing and rapid development these days.
My fucking linux machine runs on intel hardware that is targeting an arch made by AMD (x86_64).
There is no problem with sharing stable interfaces. The idea that we should not treat these as linux games because they consume an interface developed by MS, that is implemented just fine by proton on linux is... very very backwards.
Who gives a flying fuck who made the interface, as it can be implemented across platforms, I'm a-ok with the result.
You don't have a compelling argument here - step back, pause, and consider whether you're having an emotional reaction.
Your argument is basically "Developers should do things I want, for my benefit, with no regards to the success or consequences of those actions".
And that's a pretty fucked up argument.
A much better argument is: Proton makes linux a compelling platform for gaming. There is a decent chunk of market segment that keeps Windows around only for gaming. Allowing those users to move entirely to linux increases the appeal of developing native gnu/linux games, because there is a much larger native market.
This is how interfaces work - they allow you to develop new products that are compatible with the existing userbase. It's why they're incredibly important as stepping stones.
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Side note - Proton came out of codeweavers, codeweavers develop a custom version of Wine. Do you happen to know what Wine fucking stands for? hint:
Wine Is Not an Emulator.