They start out nice when they're first created, but it's really emotionally difficult to run a good one, because to be a good one, you need to say a lot of no,

They start out nice when they're first created, but it's really emotionally difficult to run a good one, because to be a good one, you need to say a lot of no, you're not awesome enough to be on this list. Like, far more often than you say yes. And who wants to be that person? A small percentage of people, and that set will be full of people who will make some other big social mistake and blow things up too. So you end up with lists that really amount to "who asked to be on the list".