Proton is just the compatibility layer, which allows you to play Windows games on Linux.

It’s one of the main reasons so many people switched to Linux in the last months and years, since Proton gets even better from week to week. Something, games designed for Windows run even better on Linux (Proton) than on Windows!

From what I’ve heard, requiring Proton isn’t that bad, especially for the devs. Often, games engineered for Windows run better on Linux than the same ones for Linux.