If you think that's stupid, well let me tell you something. You're probably the enemy of fun because that is the best thing ever. Who doesn't want to drive around on an enormous field headbutting an enormous soccer ball into victory? Fun haters, that's who. This game is actually really well made, and everything in it panned out pretty perfectly in my books.
The game is actually really simple. You and some other people aim to get the ball in the other team's goal, they try to stop you. There's quite a lot of strategy that goes into it as the people you're playing against get better and better. The angle in which you hit the ball dictates which direction it goes, for one, but even if everybody in the game sucks its still just as much fun. For a competitive game, I find it more relaxing than basically anything else I play, mostly because of how simple it is. I'll try my best, sure, but I'm not very good and if I don't lead my team to victory, oh well. At least I know the thing that's stopping me from getting better is sheer practice as opposed to learning "tips and tricks" like in everything else. (Admittedly, there are things like that in Rocket League, but I'd say you learn a lot of the nuances of the mechanics just through playing.)
You can play against bots if you don't like competitive things, too. The AI is pretty sophisticated. I'm about as good as the second best difficulty of bots, if not a bit worse. As far as fast paced games like this go, I'd say its hard to program something better than a human. Second, you can play how you want. There's online play, of course, but if you're playing to try really hard you can also play a ranked set up. Your team size can be anywhere from one to four, so any number of friends can pick this up. (For numbers higher than five, you can make a custom game and fight each other.)
What's more, as you play you unlock things like car models, decals, rims, even paint style. (You start out with all of the 'colors', meaning you can pick any shade of orange or blue you want, but paint style dictates how that paint looks on the car). After playing a few dozen games you can start really customizing your car, which is pretty neat. Sadly all of the customization is all cosmetic, but it's still pretty cool.
Lastly, this game is not only on pretty much every platform, but its also updated regularly. Last time I played there were several new game modes I didn't know existed, like basketball. I'd say this game's charm is that virtually everyone can have fun playing it, regardless of how good they are or what their gaming experience is. The key is to play against and with teams of similar skill, which can very well mean AI! Either way, I recommend picking it up, especially if you know people that play it.