This coming from a person who won the MBBA in his first season in BB.. Now now if you don't call that instant gratification, I don't know what else you can call that. BB used to be the most "instant gratification" simulation game I've ever played...
Well, what I said above is true in the sense that Spaz and I joined BB in season 3, when the MBBA was started. Gotcha :P
I would debate your definition of 'instant gratification'.
'Instant gratification' would mean gratification NOW. As in right now. Games like Counterstrike or DotA can be put into instant gratification. You shoot, tag a kill and it's added to your score. Instant gratification. You feel good. And with each kill, your reward of feeling good keeps coming. Each game lasts a couple of hours, You finish, you go home. Tomorrow you start a new one.
BB isn't like that. BB, essentially requires planning and execution for about 4 months, which is the length of a season. Even training gratification isn't instant. You plan for your matches on 3 days a week, watch and analyze them during those 3 days and reap your rewards (Or frustration at being one minute short of full training) AT THE END OF THE WEEK. The time between your players accumulating those minutes (Match time) and you getting your training reward (Training update) can be called gratification lag time (one week). If you're gunning for the MBBA title, the time between your first game and the end of the season finale is the gratification lag time. Which is 4 months in this instance and represents the time between you first putting effort to when you finally see reward.
In a lot of games, it is this lag time that sees most players leave the game. DotA barely has any lag time, you set out to kill another hero and BOOM! It's done, sometimes within a few minutes. In BB, this can be in days and it is here that boredom sets in. Nobody thinks of quitting when their team is having a close game on court, most quit when there's nothing to do for a few days and they just get bored.