Absolutely loathe the idea of moderation. I agree that there are some blind spots, but I think they're actually on the quieter boards ('quieter' in terms of absolute numbers reading and posting - SN, mental health and so on). So it's not to do with the board being bigger, IMO. It's to do with there being less passing 'traffic' in certain topics, combined with the posters on those topics already having a lot on their plates.
It's interesting that Lenin's list from feministing talks about that board being a safe haven. I think a safe haven can be achieved through the self-evolving ethos of a non-moderated board just as well as through explicit rule-setting.
One of MN's great strength is its sense of community. The prospect of being 'cast out' of the community (ie, ignored or ridiculed) for repeatedly being hurtful or abusive is far more powerful, as a way of enforcing standards, than a disembodied prefect deleting posts. The latter is infantilising.
I wasn't here when there were mods, but I can well imagine the arse-licking that went on.
(Another one of MN's great strengths is its fantastically simple and brief list of rules - so much more effective than pages of regulations that are endlessly picked over and amended.)
MNHQ possibly do need to prioritise dealing with reported posts a bit more promptly than they currently do, esp. at night-times and weekends/holidays.