@slag: From what I've seen, MOBAs have had the same growth as FPS games. It used to be that any first-person shooter that was released was immediately labeled a Doom clone, sort of like how all MOBAs were, for a time, just considered clones of the original Defense of the Ancients Warcraft III mod. Even getting people to accept MOBA as vernacular was a bit of a struggle at first. It's definitely become its own genre at this point.
That's the parallel I had in mind too and one I've been thinking about for a number of years. I always kind of wondered at what moment does a genre ,well..., become a genre. Whenever that moment was for MOBAs, I think it happened a while ago. Maybe as early as 2009 when LoL was released, possibly as late as last year when DOTA 2 was officially released. More likely sometime in between.
I've been playing DotA/DOTA 2 since the DotA Allstars days, so it's been really interesting to watch a genre get created right before my eyes.
I think part of the issue with getting MOBA as the accepted name was that MOBA was a very obviously calculated corporate label slapped on a very grassroots community, even if it was done by insiders per say. But no matter how you feel about it, I think it's pretty clear what name won out.