I can see where this is coming from. In the real world borders are more or less set since a few hundred years. Even if there are people that have cultural ties with other states inside those borders. Those people can revolt, but the border doesn't 'just shift'.
It would be nice if a tech like Nationalism or something similar sets borders permanentley, and borders can only be shifted as part of a diplomatic deal. Trade land, sell land, buy land, attack and demand land. This is what the story of the US are for example.
You won't have something like "Detroit likes Canadian pr0n too much, so now all the land around Detroit has joined Canada" nowadays. Even if they would want it
Most of the time borders only change through war.