But I'd suggest that's again because of reddit's dynamics.
Consider a different social network that is instead focused on enabling users to group with other users they deem productive (automatically, simply through interactions, or manually they can give a score from 0-100 for each person [otherwise this score is auto-generated based on signs that indicate a productive relationship). So in this social network, each person's content is effectively cooperatively curated by people they deem productive members of the network.
I believe under a social network system like this, that moderators would not be necessary. Yes the social network, as a whole, will get spammed, trolled and diluted with many many posts. But there's other systems for helping navigate this. Ultimately though, I believe the concept of productive networks supersedes the need for most moderating functions. Will there still be a need to prevent stuff like death threats or etc. etc.? Yes absolutely, but I believe that decision is ultimately an admin-level decision, not a moderator-level decision.
I also think that system would work well as long as you're interested in the people in the system, and not in topics in the system.
You bring the premise?
But I agree that in your case, moderation is usefull and important.
I hear where you're coming from, but I subscribe to a small amount of subreddits, and moderate one - and I am absolutely not willing to clean up after every troll, shill and bot that posts to all of them.
As a specific example, I moderate a local meetup subreddit. We have fairly specific rules about what is and isn't allowed, and our subreddit is better for it - because people aren't allowed to just link to random events in the city, we require that they be events that they are actively interested in attending. (The rationale is twofold - one, people won't just spam links to their events, and two, attendees will find at least one person they can connect to instead of attending alone, which can be somewhat daunting.)
If we, as moderators didn't do this, we'd have to rely on every user to "clean up" our subreddit for us. Those that didn't care to would find our subreddit useless, since it would be filled with links to garbage Facebook events, meetup.com sales pitches, and ads for competing subreddits and apps. Those that did, well, they'd have to do the work that we do.
Why should we ask that of people? It's like opening up a dance club, but telling everyone that it's BYOB, and BYOmusic, and BYOchair if you get tired, and also you gotta bring a broom if you want the dance floor to not be full of garbage. At that point, what's our value-add?