For me as a Linux only user, Proton is an incredible relief. I have all my games on Steam and can turn on Proton with a checkbox. I often use it to play old classics like The Eldar Scrolls Morrowind or Oblivion. For me Proton is a gamechanger, because a few years ago I had a second laptop running Windows and I played my games on it. I haven't had that for three years.