The Wikipedia is said to have a quality of article similar to the Encyclopedia Britannica while being vastly, almost immeasurably, larger. Some blog comments sections offer stimulating discussion and an opportunity to learn from people who know more that you do about their various fields. More have comments sections that are either shouting matches or hallelujah choruses. And most, of course, are too small to have comments sections that count at all. (This one, for instance).
All of which, I think, tells us some significant things about regulation and how it works best. Government is not allowed to regulate content on the Internet, but the Wikipedia editors regulate content in Wikipedia and bloggers regulate content in their comments sections (or don't), so they serve as de facto government of their small domain.
Wikipedia's English language section currently has between four and five million entries. Needless to say, that is much too vast for the board of editors to police. So how do they maintain quality? As I understand it, most articles are simply too small or obscure to be worth policing. Others topics are controversial within only a narrow field of specialists. Specialists are usually able to police these entries for themselves, removing any false or inaccurate information as a matter of proprietary pride. But on some hotly controversial subjects, such as evolution or Holocaust denial, the editors have to police the entry constantly, guarding against constant attempt to inject conspiratorial or unscientific matter. Self regulation, in other words, works for most sites, but close regulation is essential on the most hotly contested ones.
As for blog comments, small blogs like mine don't need a comments policy because we have so few comments. I have never had the need to erase or ban anyone, although spam entries or boilerplate encouragement dropped on blogs everywhere (itself a kind of spam) really do deserve it. For blogs with mid-sized comments sections, it may be necessarily only to remove a few trouble makers. But on a large blog, only heavy policing can keep the comments section from degenerating into a shouting match that is definitely not worth reading. This is the fate of any large comments section open to all comers. On large blogs that police their comments sections closely, some restrict only by style and some by content. Some content restriction is usually necessary to keep nuts, even polite nuts, from derailing comments. Some welcome opposing viewpoints if rational and courteous. Others limit comments to people with the same general viewpoint but allow a wide range within that viewpoint and get a constructive discussion. And some limit viewpoints so narrowly that all they get are loud, shouted affirmations, with the slightest dissent dismissed as "concern trolling." And some strongly ideological blogs with an open comments policy get the same thing, with opposing viewpoints not so much banned as fleeing the angry mob.
In short, I would conclude that in the field of discussion at least:
(1) Most entries are too small to need any regulation.
(2) The need for regulation grows as the entries become larger.
(3) Keeping order on a large site is a lot of work.
(4) Moderate style and content regulation make for the best discussion on large sites.
(5) Too tough regulation can be stifling and shrink comment down to a cheering section.
(6) Too little regulation can do the same, as the loudest voices win out and drive the others off.
Make of it what you will about the larger world.