slim viper
I keep getting stuck into disasters because my vassals cannot manage their rebels, so every time one rebellion ends another begins and I never get the peace tick I need for the disaster end condition.
But more broadly, making rebels wait for the end of wars to trigger also means that instead of being able to deal with multiple of my own rebellions at once, when my country is unstable I have to put them out in succession, even when they're quite small, which prevents me from doing all sorts of things like diplomacy.
Also, this system guarantees that if any rebellions were brewing during a long foreign war, instead of having peace after the peace deal we're guaranteed a cycle of rebellions, and there's nothing we can do to deal with all of them at the same time.
In general, this just makes the game more tedious and lagging. There's no reason for a rebellion on one end of the country to prevent another one at the other end from triggering. If the reason for this is to make instability less challenging, well, instability should have real risks. If the reason is the AI not being able to handle having multiple rebellions at once, fix the AI.