Obviously too great a keyword density can get a page penalised, as I've found out to my cost when I restarted seo after some years away, but what about too great a density of url density? If you have 1,000 backlinks and 950 of them are just the url, doesn't that look just as un-natural? Could you really rank a page with 990 url backlinks and 10 keyword links? I've seen studies that are a year or so old where pages on rebelmouse etc were ranked with url only links. No keyword backlinks whatsoever. Is that still possible?