Concurred. Pinterest is really bad. You need to create an account to do anything with it. Now I have to add -site:pinterest.com to most of my image searches.
The problem with many search algorithms appears to be that you profit massively if your content is on a highly ranked domain. Pinterest is very highly ranked so all content automatically also is assumed to be of high quality.
The same content hosted on another domain would appear much lower on Google than a Pinterest post (or a post on any other large website). Not sure if that's really the best approach but I guess it's not easy coming up with a better one.
