The only thing it has going for it is being a free beer UNIX clone for headless environments, and even then, isn't that relevant on cloud environments where containers and managed languages abstract everything they run on.
Maybe some Microsoft owned games makers will never make the shift, but if the majority of others do then that's the death knell.
Unity, Unreal and Godot all support compiling for Linux either by default or with inexpensive or possibly free add-ons. I'm sure many other game engines do as well, and when you're taking a few hours of work at most to add everyone who owns a steam deck or a steam deck clone as a potential customer to your customer base then that is not a tall order.
This doesn't make the "play" button any different. People only care if the Proton version is buggy or noticeably less performant, and native ports have no trouble being both of those (see: Rust (game) before the devs dropped Linux support)