Normies made reddit as a "socially acceptable" version of halfchan. Sort of a blend of the chans and bboards from back in the day.
The result is that it gets consumed in efforts to maintain acceptable decorum and standards. This is doubly so when you look at the inclusion of socially manipulative things such as like and dislike buttons. It has two effects. First is enable brigading - but second is it actually drives controversial behavior. Since a dislike is an interaction - the most popular things are always going to be controversial things. So the "thumbs up" seekers end up being driven to twist and distort their presentation to be controversial, combative, melodramatic, etc. These people then begin to fram the context of the conversation as their content is plastered at the top of the board.
Thus, there really is a bit of a need for moderation - but what gets moderated is the opposition to these twisted drama-queens, as the interaction fuels the site activity.