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.
https://arstechnica.com/gaming/2016/10/you-can-now-claim-you...
There was a lot of complaining online, but the class action was a minor inconvenience and they now have a pretty solid lead with the ps4.