I honestly had no issue with Indiana Jones at launch on the Deck. My tolerance for performance issues is probably higher than average, granted, but I started playing it within a few days of launch on the Deck and beat the main story within a few weeks of that. It was officially unsupported and there were absolutely some framerate hiccups, but it was totally playable and enjoyable. It actually ran better on the Deck than my desktop (also Linux, to be fair) for a while because of nvidia driver issues. The faster pace of Doom will make it more of a problem, though.

It’s truly a non-issue, unless we’re talking competitive multiplayer games. The only single player game I can think of that I’ve had Linux-related problems with since I switched my desktop over a couple years ago has been the new Indiana Jones game, and that was patched within a week of launch. Proton makes it brain-dead easy. I have a pretty big library and not many games have official support, but they just work with Proton. I don’t do any tinkering with custom proton builds or anything either. On a fresh Steam install, you have to go into settings once to enable Proton in games that haven’t been tested with it, but then you just forget about it and play like you would on Windows.

Evolutionary psychology. I think there’s real research in the field, but it’s drowned out by charlatans who use invoke its name to lend credence to their made-up bullshit without the burden of scientific rigour.