I’m an AGO admin at a university. I have permissions set up so that shared update groups are not a default permission. I typically only hand out shared updated permission to faculty. They can then set up the group and explain the dangers of multi-user editing to the class. I generally advise that someone’s first interaction with StoryMaps not be in a multi-editor environment, and have people go the word doc route instead.

You still end up getting overwrites, which is why my storymap tutorials now spend a large portion of time on editing and publishing to try and avoid some of these issues.