They also removed trading for epic's stupid rocket racing mode that died within a month, made dropshot and snow rotate with each season causing people to throw because who cares about a seasonal mode, servers getting worse every day, doing nothing to stop the smurfing and boosting problems, GC level bots still in ranked (although not as much), invisible players, cheaters able to fuck with the servers and cause disconnects/lag, and just general toxicity from the player base that they won't address.

Do you need an Epic account to play if you already have it through Steam?

Bingo. I was a Steam, Linux, and Mac (IIRC) player.

But this happened after the Epic acquisition though, the game had Linux support from day one then Sweany came in.

Rocke League before Epic was great and I wouldn't consider Psyonix a bad company.