There has been for some time the option to play on "safer seas" where its basically a private server for your party, but you get lesser rewards.
halendos
For a single-player game...
I started playing a year ago (also on Linux), I never felt a lack of players to do anything, be it recent or older content. As for performance, from what I can compare with my friends, its runs at about 90% of windows. It's free to play the base content, give it a try!
Man that game is a damn masterpiece
What a shame, he was a good man.
Website hosting costs most likely.
I had that issue for a while and it turns out I forgot I had an extension changing my user agent. After I changed it back to default everything worked fine.
The issue that everybody seems to forget is that orcas are not damaging/sinking those > 50m yachts from millionaires, they are targeting smaller sailing boats (still called yachts), most of them from your average Joe who just wants to chill under sail, like me. Now I get very nervous every time I go to sea because of the attacks near the shore.
So if indeed orcas are "rebelling", it's the people who have nothing to do with the issue that are paying, as usual.
Sorry for the rant.
Linux gaming is at a point where the only games that don't work are the ones being actively blocked by the developers, mostly through anti-cheat systems. Just install a stable distro like Ubuntu or Fedora, and use Steam, Lutris and/or Heroic to manage the games and compatibility layers needed for them.