The thing with the M.U.G.E.N Fantasy League was, a lot of characters needed patches just to stay balanced for competition in the League. Those same patches, by contrast, made them absolute monsters in Arcade Mode, meaning that if you got the patches but weren't making videos for the League, you were basically screwing yourself over if you just wanted to play Arcade Mode. Worse, even with the patches (or characters that didn't need them), there were A.I. imbalances and other issues that turned what should've been evenly-matched bouts into squash matches.
I'm not saying the League was a bad idea....it just needed to be refined.