It's supposed to be that you're never stood up unless you're trying to simply hold a dominant position to stall or rest.
I understand the argument that a guy should be allowed to blanket you for a whole round and win it, and it's up to the other fighter not to let him. I actually used to argue that. But I've changed my mind on that. I think if you establish a position and just hold it, the ref should separate you if you're just stalling (but obviously you still showed that grappling effectiveness to the judges.) The reason I've changed my mind is that I don't think it's effective enough to be a legitimate fighting strategy. If you're so good at holding a position that you can just smother a guy round after round, you should be able to do enough damage to make it effective. If you're just a backpack, and the other guy comes out of the fight no worse for the wear, than all you really did was deprive the fans of a fight. You made a fight not happen. That shouldn't be encouraged.
I also used to argue, and I think this is still a legit concern, that standups encourage the bottom fighter to just hold on praying for a standup and not to try to use sweeps or take risks to get up. So the ref needs to know when it's the dominant fighter just holding and stalling time, and when it's the bottom fighter just holding because he can't do anything else.