Why so many "newer" Mac's for sale?

I can't be the only one who has noticed that there are a lot of newer pieces of McIntosh's being sold here on the 'Gon. Most of these amps/preamps are quite pricey to purchase, so I'm curious as to why these are coming up for sale so soon. I can understand the "older" stuff being offered for sale. Are the newer ones not that great? Or is it the old "never satisfied" issue coming into play. Just curious!
Alan