In the post I linked, they talk about issuing refunds and that the game is played well via Proton, so I wouldn’t classify that as telling the users to get effed. And again, it’s not unheard of for games and software to no longer support specific operating systems after a while. If you’re a Windows 7 user, your whole Steam library would become unavailable unless you switch. Sure, you can upgrade, but a Linux player of Rocket League can also switch to the Proton/Wine version, which is even less drastic.