Do you remember the days before proton? Like the time I couldn’t play Terraria for months because they didn’t have anyone in their dev team who could update the Linux version to keep it working. The workaround was to get the windows version working through wine.

Using wine to play windows games is something we have done for years before proton made it easier. It’s a very Linux thing to do. Even some old ports were just using wine wrappers.

Do you like the half-maintained and rarely updated Linux builds more? I sure don't.

It makes perfect sense to do this. You have no idea how much extra work it is to maintain a Linux-native version that works predictably across the entire range of Linux machine configurations. Factorio has one guy, raiguard (hallowed be his name), in charge of the Linux build, and he wrote a blog post about the unique challenges of supporting the Linux native build.

Proton is already known to be perfectly capable of running most games as good as or even better than Windows. Game developers can defer the issue of compatibility and focus on developing the game instead of having to implement client-side decorations for GNOME users.

Why?

But it requires getting more of the team on Linux :)

Get them a Steam Deck and target only Steam Linux Runtime 3.