@casper It's a state saving system. So it's similar to [sssad] in that respect.
The benefit of preset_hub is that you can put
[preset_node foo] in an abstraction and it will find the
[preset_hub foo] in the parent patch automatically.
Additionally, if you want to fully encapsulate the state saving within an abstraction you can also achieve that without $0. Just put preset_hub inside that abstraction and you won't get nameclashes with any preset_hub by the same name in a parent patch.
In short, it is a state saving system that gets rid of the necessity of passing $0 around at all. That, and it doesn't require you to make connections from the relevant object back into an inlet of preset_node. It just works automatically which is a big UX gain.