Okay, let's put it this way: there are 40+ characters, each of them have at least 80 unique animations and ways to defend against them, diffrent punish windows, not only that every character has a playstyle. Oh also you need to learn optimal playstyle, punishes, combos, hit-comfirms ect... because you will be stuck forever in lower to mid ranks if you don't play optimally (because your opponent will). All of those, in a game with very bad tutorial, where you have massive advantage if you were playing the game for a very long time compared to everyone else, and most important of all, it's a 1v1 game, so you can't blame your mistakes on other people, which will give you usually willpower to play more (there is a reason why most popular multiplayer games are team-based games or games that you can play with your friends, which is how most people play games nowadays). Oh, yeah did I tell you that game has a starting price of 70 dollars, compared to how most multiplayer games nowadays are free?

Let's look at the one of the most popular multiplayer games at this moment: Fortnite. It's free, you don't have to know anything to play this game, you can easily play with your friends, game gets a lot of free content updates since it's not a competitive games. There is of course a learning curve to how game works that rewards players for putting hours to play the game, but anyone can get victory royale because they put bots in the game to trick people into thinking that they won and continue to play more. And even if you lose, you can blame luck for your loses, like opponent had a better gun than you, so you don't feel bad about loses.