Epic also owns one of the largest "anti-cheat" software companies. That refuse to support linux, or work with Valve on making it work on proton.
There are quite a few games that work great with proton, but can't be played online because the anti-cheat won't run. Like Arma3. It runs great in linux, but the binaries are always 3-6 months behind the windows ones. so your choice is to find a server with 2-3 people on it, or run it on proton, see lots of servers with hundreds of people, and can't connect.
Don't Epic make Unreal Engine, which supports Linux? I'm not sure it's fair to say they do nothing, if that's the case.