This is a fairly niche issue because its only really a big issue for 1 civ on 1 game mode. But, ending out a game with Lakota on Treaty is very difficult because of the block radius of the enemy Town Centre.
Basically, Lakota rely on Tepees to buff up their armies. At some point, you will not be able to build tepees to push into the base because of the enemy Town Centre, so you have to rely on their unbuffed stats to close out the game. This can take what should have been a 5 minute siege into a long drawn out one for no reason other that the block radius. Lakota already struggle with sieging, but to do it without tepees is a big ask for the civ and their units without the buffs cant really compete with similar units of other civs.
I cant think of a purpose as to why you cant build next to the town centre of the enemy, it just seems like a forgotten relic from the past. It does affect Lakota the most, but there are occasions when it can unnecessarily pre long a game with other civs too. So I think it should be removed or at least make Lakota Tepees exempt from the block or at the very least reduce the radius greatly.