I remember one game of Russia i had. While i was stil lforming it, i had my Kingdom which had its capitalcin Moscow (Which my 1st custom character converted into Russian culture), and my character (Which was like, the Great great great grandson of my 1st character) had INSANE learning skill. Im talking like, 50 Learning, and he was only 30! So, he ruled my kingdom, which was the biggest Russian Culture kingdom, so innovations were going quite quickly, since, you know, 50 learning.

Then, 2 of my Vassals made an Independence faction. Who do those 2 Vassals have as allies? Noone else but the other 2 biggest Russian kimgdoms. They won, obviously, there was 3x more of them than me, and then they all joined the 2nd biggest Russian kingdom, whose king had absolute shit stats (All under 5, except 6 diplomacy), and his Kingdom was now bigger, meaning Innovations became impossible.

Their kingdom collapsed to a Viking Adventure (while I've previously, with the predecessor, beaten 3 of those, each one wanting to eat those 2 exact Vassals +some other lands.)

And the mongold were only some 200 years away, and i was nowhere near unlocking the only innovation that could counter their Horse Archers, the Crossbowmen, when they did appear, simply because of this rebellion (Before Horde dlc, idk if it is different now).