The elbows aren't the problem on the ground. The only way to keep the game fast paced and exciting is to have refs that will stand people up when neither is being strongly offensive, both the person on their back and the guy on top. Pitter patter punches from guard or side control are boring, but so is a guy just holding the other's posture down in guard. However, if the the guy on bottom is active and constantly going for submissions even if the guy on top is not doing anything, then of course the ref should let it stay on the ground. I see it as if the guy on top is just holding position, pinning the other on his back, and not trying to deal any damage, there is no reason he should be allowed to sit there, it is not just boring, it is as useless and passive as someone constantly running away from their opponent when standing up to avoid getting punched. Landing a takedown and laying on your opponent is literally as bad as landing one good punch at the beginning of the round and then staying out of range waiting for the bell in my opinion.