The highlights considering what the conversation usually is about when referring to "moderators" actions:
* There's a process that deletes posts that are old and haven't seen a single positive interaction [1]. This is the biggest responsible for deletion of post for the site. Then users, then elected moderators. In that order.
* Authors are the ones that most close questions. This is due a mechanic [2] that allows authors to accept a suggestion that their question is a duplicate. Non-authors and moderators represent a relatively small part (~15%) of all closures of questions on the site.
* There are certain actions that only elected moderators can do and no amount of coordination by users are capable of, because of their sensible nature [3], those are the special attributes of moderators. Anything else most users can accomplish them.
[1]: https://meta.stackexchange.com/a/92006/213575