Google Bombing. Stopping the growth of positions on a particular keyword. The reason – the fastest growing links with the same anchor. The expediency of his dubious enough, particularly with regards to non-profit requests. Remove it possible, for example, diluting a lot of referential anchors with surrounding text, and indeed strengthen its trust links. The reason for the introduction of the filter was actually 'guglbombing' – bulk purchase options (Often by many people) with a single text for a particular site and then to push him through some absurd request.