There is steering sensitivity, car speed, ball speed, car mass, car power, boost strength, shooting power, jump height. All those variables have been finalized. What I'm saying is that balance patches are a band aid over the core problem.
What’s Rocket League like nowadays? I only played when it first came out. The impression I got though was that it was more like Counterstrike or something: mechanically simple with lots of depth, designed to be more like a sport than a game.
Overwatch is pretty casual. It is tuned for spectacle, and the abilities work out such that most reasonably non-bad players get a steady trickle of moments where they get to be the “star” for a scene.
It isn’t really a core problem, just a different type of game.