I have this tinfoil theory that RJ separated Finn & Poe’s stories in TLJ not because “their dialogue was interchangeable”, but because he was considering making them a romantic pair and we would see that develop in their journey. When Disney gave him a big NO, he still wanted some romance, so he separated their characters and added Rose.

I don’t really believe this, Rose and Poe are pretty distinct voices from each other so I understand that story decision, but if it ever turned out there was some truth to it I wouldn’t be surprised.