Posts haven't been deleted. The post count was reset. Moderators don't need to show up on the list, and since certain posters were permanently lodged on the list, with no hope of anyone else ever nudging their way in, we reset all those with over 1,000 posts. One of these was by request.
Who posts how many isn't really important, now is it? The primary purpose of the 'top poster" thingie is to fill space on the front page.
Now for your enjoyment, a musical interlude:
http://www.youtube.com/watch?v=mW0B1sipLBI