To quote House the Brotherhood are just a bunch of terrorist. Look how in New Vegas where they murder Followers of the Apocalypse in cold blood. In 4 they get even worse becoming essentially Caesars Legion with gender equality. They have no real purpose now that the most technology has been reintroduced at some level to the Wasteland. All they do now is kill and break things, raiders with delusions of morality, basically Caesars Legion.