Approving a node just means that it will show up in a section. A minor sanity check by users that are (supposedly) experienced enough to know better than letting a post saying 'Some dude wanted my script, so I ****** it and gave it to him' (You may remember seeing this in newest nodes for a while, but it never made a section).
in reply to edit top level nodes?
And, you'd have to promise not to edit comments if someone started hammering on them (I'm not starting anything here, but any recollections of that happening in the last few weeks?)
Admittedly, I can't see a major difference between editing a top level node and a reply node. One difference may be that top level nodes show up on the respective pages, and are more "visible" than other nodes, so it prevents someone posting something innocuous, then changing it to a nasty-gram. Just a theory, tho.
Personally, I'm of the opinion that once you've been around a certain time, AND made a certain number of posts, AND have a certain level of XP, you should be able to edit your top level nodes... Kind of a 'with rank cometh priviledge' kinda thing.