Its purely for dead handbook recovery and maintenance. We have quite a number with missing or collaborative authors, which could use an editing mechanism. Thats about it.
While I understand the intent, Veekie, I still will remain one who dislikes the idea of a group of people (rather, a number of individual persons) capable of editing other people's work as deemed necessary.
Though this may seem petty (I hope it doesn't, but I'm not naive enough to think people will not take it simply as childishness), I want to be clear about my reaction: aside from the Rebuilding Handbook (which is insular, and should remain so), and the two treatises I've introduced for the 4e boards, I will not be writing any more handbooks as long as there are others who can edit them without my consultation if they judge my work to be incomplete. I am not opposed to processes of editing at large - I am a writer, and I understand well the value of editing - but the total authority of it (which I also understand well is a contingency against missing authors who cannot be contacted*) leaves a bad taste in my mouth.
I do take pride in my work, for better or for worse, and to be unsure that my work is remaining mine out of the judgments of other persons is not comforting. Further, to clarify, there are periods when I will sometimes not visit BG and may be unreachable. It is not unthinkable that someone might conclude that I have gone missing, as even when I am around I see much and post little.
As regards collaborative handbooks, perhaps I don't see the advantage over the account-sharing approach which has been popular.
*Fixing one problem and creating another - as SorO points out, the very problem the moderation limits were built to avoid - seems the worse option when you could simply delete or (preferably, for a community built on the learning process of optimization) archive threads that have outlasted their usefulness and been replaced with more thorough handbooks which give credit for their inspirations, which may include those very outdated and abandoned handbooks.