

I’m going to do a hard disagree here - they don’t have to support Linux, just add compatibility in terms of anti-cheat for Linux. Proton is likely good enough to run the game itself but the anti-cheat sees Linux and just craps itself.
They don’t even have to provide support - League of Legends runs on Linux if you install the game using community scripts and custom proton, and while the client runs poorly nobody spams the Riot Games support about how the “Linux version” client doesn’t work the well because people understand that it’s a community effort. Riot themselves have only made a statement saying how they’ll try not to break the game for Linux users, and that’s pretty much it.
League of Legends is a massively popular game as well, yet Riot barely has to do anything to maintain it on Linux, let community fix issues that come up, let community provide support as it’s their tools.
And while I do understand that porting an anti-cheat to be more friendly to another operating system isn’t an easy task (such as for Rust, where they tried to make the anti-cheat compatible with Linux but it introduced other issues so it got shelved), I think you’re vastly overstating the amount of areas a company has to cover for a game to be playable on Linux.
The problem with difficulties is that it’s much more difficult to design an AI system which you can tweak and make it smarter or dumber as opposed to just increasing damage and health values, so devs will just implement the best AI they can and leave difficulties as afterthought.
After playing a lot of games that don’t even have difficulty settings, I’ve started to believe in the idea that difficulty selection is just outdated game design and that having a single difficulty but optional areas/content that is more difficult is the way to do it. OSRS is one of my favorite examples - everyone plays the same game and going through levelling or whatever isn’t mechanically demanding. However, there are bosses and challenges (like Theatre of Blood which is an end-game raid or Inferno which is an end-game challenge) that are incredibly challenging and require weeks if not months of attempts to master and finally beat, but also are perfectly skippable and most casual players don’t even bother with them.