There's a lot of reasons why fighting games aren't as popular as those games. As a street fighter/Marvel player, the big ones seem to be:

Developer support. Nintendo actively suppressed competitive melee for a while, and killed PM. They're better now but look at Riot and Valve: they have built in professional circuits. And let's not even begin with the bumbling idiocy that is 2016 Capcom.

Steep, entry level skill curve (smash may not have this). Getting to a tournament level in any game is hard, but Street Fighter 5 is the most barebones, easy, newbie friendly traditional fighting game out there, and it's still really hard to get the basics. Ryu, the most basic character, has 3 special moves, each with 3 versions, each with different inputs and uses. At least with Smash every character does all of their special moves the same way, so new players have less to learn in the beginning.

1v1 means that losing is 100% on you. There's research that shows that bad players stick with MOBAs because they blame teammates for losses and think they're improving even when they're not.

Historical context. Fighting games rose from arcades, and a lot of the players who got really good did so because they only had arcades to play in. There's not a lot of money to be made from these players, so the investment isn't that lucrative. I hesitate to even cite this, but I think it does play a role in the "culture" surrounding the Fighting Game Community.

Overall I think fighting games are the best spectator eSport. Only 1 screen to watch, 1v1, you don't have to understand anything about fighting games to understand who is winning, but all of the underlying strategy is still there. It sucks that they aren't as popular as MOBAs because I think they present a hell of a lot better on TV.