You overestimate the skills of moderators... I doubt very much that true experts in their fields would spend any time doing moderation Reddit... most likely, people doing that would be recent graduates trying to learn and impart their recently gained knowledge upon laymen.
There are several subs I'm aware of which do seem to garner expert-level moderation.
The Asks -- Science, Historians, possibly Economists (I'm trying to decide there -- the mods talk expertise, though quality IMO lags). Several of the Fitness subs are quite good. Various technical subs attract high-quality contributors, and the CSS support sub (specifically for styling old-style Reddit custom stylesheets) is simply superb. I've dug into energy topics, and though there's a bit of BS flung about, there's also quality expertise.
Posting online actually is a form of shingle-hanging and getting a sense of issues people are facing in the real world. There's value to that.
