Twitter for example has both.
- https://dev.twitter.com/rest/reference/get/followers/list Which has a limit of 200 (similar to the current Twitch one with a limit of 100)
- https://dev.twitter.com/rest/reference/get/followers/ids Which has a limit of 5000 (this would make it easier to get the full follower list with less requests, especially if you already have the other user info and just want to check if a new user has followed or an “old” one has unfollowed)
I would even say that this approach could be used for the following and the subscriber endpoints too.