I can understand the need for it, even if it does appear a little odd on the surface.
If you go and edit a post, the action is deliberate and requires some amount of effort on your part; you must actually look at the content of the post and (hopefully) determine that your edit is both sensible and relevant.
While the same thing should take place when approving an edit, it's much easier to miss something that's amiss with the edit. In this case, multiple eyes is probably a good idea.
Secondarily, if you edit a post yourself, your name is displayed prominently on the question or answer.