The PFLP was crushed and the Muslim brotherhood associated Hamas was raised in its place more or less by America/Israel. Hamas aren't the PFLP and have very opposing general ideology. There's members that went from one to the other cause it's a desperate game and you go with the resistance that's in town. But there's a reason it's these guys, it's cause they also kinda suck and it's easier PR for Israel to fight Islamic fundamentalists than secular socialists. They aren't the same organization and aren't by any measure an ideal government to tske hold of a united Palestine, but they're the guys we have.