Pulling support for a client of a competitive online game like Rocket League is fundamentally closing the game to those players - as they will be unable to compete online with other players (be it on PC or on the other platforms).
I really don't like Epic's change in behaviour here - It's quite disheartening since when they used to release first party Linux builds of their products ('Unreal Tournament 2004', and the recently cancelled upcoming 'Unreal Tournament' had Linux client releases), and they were one of the few big name game dev houses to actively support Linux clients.
Other than Unreal (the game), there was hardly any big effort to support GNU/Linux from Epic side.
Exclusivity has no place on a decentralized market. When Sony and Microsoft do it, it’s still reprehensible, but understandable. This is inexcusable. People defending such deals (including Sony’s or Microsoft’s or Atari’s) are idiots.
I understand where these companies are coming from. I would too love to have more games available to me on OS X but the simple fact is there are not enough customers to spend money to develop directly for it or even contract out to a software house to write a wrapper. Let alone how many complain how much the games or DLC cost are worse on some platforms compared to others.
Now it is more profitable to get cross platform with PC and game consoles.