User blog comment:MakeShift/Integration of cast sections into episode pages/@comment-25054842-20191221141551/@comment-31722073-20191221143317

I'm going to guess the same reason other wikis have them, it allows to better show cast information by showing the whole cast and is more visible, and if you're going to be changing the cast format of some episodes why not just go all the way and create a more effective section.