From what I've heard of the show by listening to detailed reviews, I can already surmise why the black hobbits Harfoots got genocided. Apparently, their leader, who is of course black, has a policy requiring anyone who can't keep up with the rest of the caravan to be left for dead. Even if they're injured and unable to carry their cart, their cart has broken wheel, and so on. Oh, and entire families are punished by getting moved to the back of the caravan to make leaving them behind easier, while the higher status ones get to enjoy being in the front, where they are free to control the pace of everyone behind them. And anyone who goes to help someone who's lagging only risks getting dragged down themselves. Yeah, like that policy's never going to become rife with abuse and grow unpopular...