looking at the state of 4chan now, it's a necessity to have mods enforcing rules, to keep the quality of the boards. let's look at the most unmoderated board on all of the imageboards:

4chan's /b/.

current threads as of 2008-5-1 4:20PM

-post ending in x tells me what to do
-I am feeling emo
-europe vs USA
-reposted image asking for "MOAR"
-Personal Army Request
-post ending in xx gets y

in other words, stupid crap that has been done several times before.

moderation is needed (in moderation) if you don't want your board to become a stupid piece of shit.