I think a game is a good example, or anything that's kind of like a game in that it's modeling a world that's changing over time. Objects come and go, and they "target" each other or "require" each other or whatever sort of relationships the program wants to express. Those relationships end up forming a graph that might contain cycles.

I just put up a blog post about this actually :) https://jacko.io/object_soup.html

> promoting the shared state to a container object for the set

Yeah I think that's a good way to describe these "ECS-ish" patterns.