I certainly haven't visited all of their pages, but it seems that the top 21 in these lists are certainly deserving of their rank. The pages of those that I have visited are quite active and tend to provide a wealth of value to the community. Still, I do think that a decay system would be valuable--kinda surprised that the designers of the platform hadn't included something like that as base functionality. Knowing that you've gotta keep working to earn those votes would certainly serve to keep the top performers performing.