the tournament scene is helped by the internet which was too primitive to be of use in the 90s. the IPs are too niche now to have the same marketshare that 90s fighters had.
What’s your point? It’s still more popular just like every other genre since gaming has evolved. And titles like smash and DBZ aren’t niche. But the fact is there are more fighters now than just SF and MK of the 90s.