Why in gods name would a game remove trading after it'd been around for a while?
I don't play rocket league, so I don't know how good psyonix is with the community, but from the article it makes it sound like this was entirely epic's decision. Sure, every game is going to wax and wane in popularity, so he would have had to find another source of income eventually; but he wasn't afforded the luxury of having time to pivot when the site's revenue started dropping too low because the rug got pulled out from under him. He was given the impression by psyonix that they liked his site by giving him an in-game flag and (it sounds like) special API access, and now they're suddenly cutting ties to him.