I would prefer if there was a secession among my enemies. Rebels as you describe them are hostile to everyone and I would have to go over there and make the area either mine or a client state etc.
Dropping the province stability is not that hard for me, because I have a mod that allows me to sack (loot without occupy) installed. I can go to a province and wreck it and then keep the armies of the enemy away so that the rebels take it over. But if I do that, I won't be able to trade with the rebels etc.
The ability to incite a -20 to -60 to a province
actually scares me. If my minor faction enemies do that to me, I am screwed.
I used to use dignitaries and destabilizing actions (like burning cultural buildings) in previous campaigns in the past to incite rebellions. Now with the sack action and being big and powerful I can save the money and destabilize them with armies.