Marvel has always been a little more lenient than other Capcom fighters in that regard. In a lot of older games characters can't even throw another projectile at all if a previous projectile is still on screen.
That's how it is in SF4 so it was definitely intentional in that game at least. And on CPS2 games you could have more than one fb like in marvel or sfa custom combos.
This was a problem several months ago from my experience (PSN), not suprised to hear it has gotten worse. I played a lot in the New York lobby, but the dudes were from the UK.
Every time I go on, there are only people in the NY room, and sometimes the LA room. Very rarely the SF room. Sometimes other random cities say 10% or something.
I hope they take the online structure in another direction for SC6. At least I hope there will be one, heh.