I’d like to better understand this special group, but my searches here aren’t turning up much that’s helpful. Or is this really all there is to know about it?
The @staff group is one of the automatic ones so people can’t be added to it manually like the other groups. It’s essentially the @admins and @moderators in one combined place (‘site staff’ rather than company employees).
So Dax’s post you linked is pretty much the long and short of it: