Actually I'd say it has hurt it. Perceived excessive moderation on various boards is why people left to go to 8chan, where you can make and moderate your own boards, so long as all the content is legal.

I'd rather have no moderation than lax moderation, which is why I'm in favor of decentralizing imageboards; the nntpchan software, which is an imageboard over nntp, is very good for this. Perhaps some system using bittorrent technology, too.

To reply to astrange (I am unable to reply using the usual method because the HN mods don't like it when I post quickly, so they've stopped me from doing that, ironically in this discussion about moderation):

I wasn't trying to say that 8chan is unmoderated, I recognize that it is moderated, because of the "only legal content" rule, rather I was trying to say that an unmoderated imageboard could exist in theory, but an imageboard which insists on only legal content is of course moderated.

4chan's moderators are in an unenviable position. For example, a large number of users left because the moderators put their foot down and decided that the site would not be the base for a widespread Internet harassment campaign.

Are the users haemorrhaged from that to the detriment, or the benefit of the site?

That's largely a matter of opinion, and you must factor in what counts as a detriment or benefit, which varies with 4chan's goals. Arguably 4chan doesn't really have a goal, though some (particularly the alt-right type people) would say it's a detriment, and people like me or some users of non-political boards think it's a benefit, as one of the large concerns is that /pol/ is infecting other boards, despite the fact that it was made as a containment board.

Others boards such as /mlp/ however do not show such growth into other boards, perhaps because the rule against ponies is stronger than the rule against racism.

"Containment" boards are pure fantasy, they just give the worst users a place to coordinate their attacks on other boards.

You can't have "no moderation" and "only legal content", and I don't think you've thought through the consequences of picking the first one. Law enforcement actually really does exist, you know.

Most people are not fans of unmoderated message boards which is why 8chan is the fringe of the fringe.