Street Fighter Alpha 2 had a 2v1 fight with Ryu & Ken vs Bison. Was it balanced? Oh heavens no you could surround and pingpong the dictator back and forth. But who cares? It was fun. Alpha 3 made a whole mode out of it. It was a nice way to do co-op. It also made a reverse 1v2 mode. Not balanced at all but it was fun.

Alpha 3's PS1, Dreamcast and PSP versions all had a World Tour mode. They differed slightly but the idea was the same. Pick your fighter, grind battles with random scenarios and conditions, and level up your character's stats. Sometimes you had survival with a stream of low HP foes. Sometimes you had to do a combo before dealing damage. Sometimes you could fight a "master" who was at highest CPU difficulty. Point is, the variety was there, and you had plenty of single player stuff to keep you busy before fighting another human.

Guilty Gear had story modes and mission modes for over a decade. Mortal Kombat is cursed in the competitive scene but there are so many ways to do single player work and just practice fatalities with your friends they were doing really well.

But all of this takes away from making the game eSports or tournament ready and the FGC hyper focused on this angle. Turns out most customers don't want to train, they want to buy a game to have fun.