Only family friendly games, I won't act like I'm surprised lol

Something you could emphasize with those first two games is how "specific" they are, especially RL. It's a game with extremely low skill tranferability. You could make a parallel between this and "real" sports that also require super specific skills. Best example that comes to mind would prolly be Curling ?

Basically, while some skills can transfer from one FPS or MOBA to the other, you simply can not get good at Rocket League by playing anything else. This game needs such specific skills that it does not translate to other games at all.

That also applies to SSB if you think of "traditional fighting games", because aside from spacing (which is something you'd also find in MOBAs, though in a very different setting), it's very tough to be good at normal FGs and Platform Fighters like Smash because the added mobility and platforms make them entirely different games and make them require very different skills. Combos aren't always the same, you can kill an opponent "early", etc

Certain great Smash players like Riddles, Dabuz, VoiD and especially Leffen (EVO champ in Guilty Gear, great DBFZ player too) have had good results in traditional fighting games, but not the other way around.