Like everything else, there's an element of truth to it, but it's probably unfair to make that sweeping generalisation that higher dot colours get better ratings.
Some do/did. They went out of their way to court people and reaped the benefits of forming these relationships. However, this behaviour started when they were new to the site. If you get enough people E-ing you, then the sheep follow suit. These people didn't suddenly start getting Es because they had turned bronze or whatever.
Plus, you're dealing with a site full of mentalists that have absolutely no concept of peer review and are too busy leaving each other GB messages to worry about review or rating integrity.