When you do purist route and occupy an occupied province with more than 30% resistance the province immediately flips to being Lawless Wasteland and ♥♥♥♥s really hard with your front line. This happened for me when i attacked the NCR and so did BOS. BOS occupied a lot and the resistance got higher than 30%. When i invaded them the provinces kept flipping since the resistance was over 30% and it became really annoying to keep managing your front lines.