Apparently this game requires libc5 or something which is a hassle to get running on any modern system (YMMV) so using Proton is easier. Given that WINE (and by extension Proton) is built in part to allow running programs made for very old versions of Windows (i.e. it also aims to aid software preservation) it kinda makes sense that a game that's been updated the last time over a decade ago would work better in that environment than one that's built around maintenance (by means of distro updates).

Either way, using Proton was pretty much plug&play; go to the game compatibility settings, check the compat checkbox, choose pretty much any Proton version, start playing.

I still very much appreciate developers putting in the time and effort to build a Linux version (especially nowadays that it's often just the click of a button to do so), and here I know it used to work once upon a time, it's just that time has moved on since.