Is it really nepotism? There are things like proper equipment, speaking ability, and so on that make an important baseline for indies. But pass that line of normalcy, pass that line of mediocrity, what really matters is getting people to actually FIND you. So you network and you become friends with the people you do, or it happens the opposite and you become friends on some gay discord and then collab for visibility. If Holo, Niji, whatever seeks talent only from relatively popular indies it's inevitable that they all know each other. It's also inevitable that they share a lot of the same personality attributes, sense of humor, talents and whatever.
tl;dr The indie scene is going to provide an endless amount of women that can sing or draw, have little interest in games, are mildly funny, and they all know each other.
