jb, my point is I'm not interested in tracking and I'm not interested in showing trends over time. I don't need a web service to tell me what I've been listening to. I'm interested in showing and sharing which tracks I really like, which is what syncing ratings and playlists would be better at for me. For new signups especially, just showing which tracks have been played most frequently isn't necessarily indicative of what their real favorites are.
For example I've been listening to Symphony Ys 21st Century a good bit over the past couple weeks as it's a new acquisition, but it doesn't hold a candle to Symphony Ys '95, which I'd much rather encourage people to listen to but haven't played as much myself recently cause it's been in my collection forever.
I used Last.fm for a while and though it was fine for showing which tracks I'd been listening to recently, the overall favorites that it had mapped weren't the ones I would most want to share and recommend to other people in reality.