These ports are also not usually source ports, so they're not much "more native" than the Proton ports. They often use the same kind of API translation layer, probably also built on WINE. I think as Proton sees more investment and becomes more advanced, it's probably becoming difficult for competing compatibility layers to keep up.

A source port that is optimized as lovingly as its Windows counterpart will probably be faster than the Windows version running via Proton, but the incentives aren't generally there to justify the costs/difficulties. Maybe some day it will be! That would be wonderful.

But until then, Proton seems like an increasingly compelling option for these compatibility layer-based ports of Windows games.

> and get their game running perfectly under proton

Even better would be to compile for linux, but use DXVK-Native (https://github.com/doitsujin/dxvk#dxvk-native) if you think migrating from DirectX to Vulkan requires too much effort.

They probably QA mostly for windows, so they run into bottlenecks and edge-cases of windows APIs during QA. Linux-native APIs probably have different bottlenecks and edge-cases.

I think the reimplementations of Windows APIs in Linux, even though alternative to the original, should have similar bottlenecks and edge-cases. So the extra QA on Windows helps the Proton version more.

But maybe figure out how to start getting those third party Linux porting studios paid to work on Proton...

To be you should compare the windows version on windows, no proton against the Linux version. DXVK, which proton uses, makes some games run better in windows than "native".