Everyone is comparing apples and oranges. The truth is that Capcom games have undergone minor iterations for decades. If you've been playing more or less the same games for years, you'd also probably be good enough to add side games to your arsenal.
SF4 is an iterative improvement on previous SFs, as is MVC3 on MVC2. Which was an iterative improvement on Marvel vs. Capcom. Which was born from X-men vs. Street Fighter... Etc. Imagine if people had been playing versions of Injustice since 2000. Instead, we went from classic MK to MK3 (which had all kinds of system changes) to MK4, to the modern 3d MK era, to MK9 which was a new hybrid, and now to Injustice which is a totally different game.
If we'd been playing iterations on Injustice or MK9 for the last decade, squeezing every last drop out of the game's fundamentals, we'd probably be leaps and bounds better at it than anyone else. Just like the people who have been playing Tekken forever. Instead we have a game that was literally a completely different type of 3D fighting game (and somewhat of a broken mishmash) 2 iterations ago.
In addition, while SF stayed in arcades, MK made the transition long ago to home systems; which means that the highly competitive arcade culture (and the conversation of tech and ideas from Japan's arcade scene) that created the current Capcom environment did not exist in our scene for a number of years. There were a few hardcore devotees and that was it.
(Again not that it would have mattered as much, because the game completly changed with MK9 anyway).
So the moral of the story is that people need to stop comparing these scenes like they're equivalent or are somehow built from the same type of resources as each other. They are 100% different worlds, and trying to equate them is an exercise in futility.
Play what you play, and be proud of it.
:16Bit