Hacking the ZhurnalWiki is simple: find the "Edit This Page" option in the popup menu next to the "Page Action:" button. Then monkey with entries by hand, or if that's too slow craft a simple script to do it wholesale. But why bother? There's no glory, and somebody else will quietly repair any significant damage.
Classical Wikis have no security to speak of. It's rather like leaving your doors unlocked at home. Neighbors can come in to help if there's a fire, or if you fall down and can't get up. You can enter quickly if you forget your keys. Life is simpler and more efficient. (Yeah, stuff can get stolen --- but should one be so attached to one's stuff? I dunno ... )
DNA sequences in real life biological systems tend to accumulate "junk" --- sections that don't seem to represent useful information for building proteins or doing anything else important in a cell. (See the portal http://junkdna.com ). Maybe a Wiki is analogous. Material builds up over time that doesn't seem to represent useful information: silly cross-links, typographical errors, mistakes of fact, self-promotional hype, etc. But it doesn't really harm anything and the cost to carry it along is less than the cost to cut it out. And maybe someday the seeming-junk will turn out to be valuable in an unanticipated context.
(see also FragileBeauty (15 Sep 2001), ... )