Sort of tongue in cheek, but the visible effects of moderation are awful in 90% of circumstances across the internet. Granted we don't see the benefit of the non-visible parts, but on reddit especially there are endless stories of communities being ruined by moderation, and moderation being used to force community behavior that suit the moderator's agendas.

There instances, like HN, where the platform isn't trying to be used for making money or pushing an agenda. Moderation on this tends to be good, but that set of circumstances is rare