Repeating a keyword or search phrase over and over again on a page in an unnatural fashion just to raise your site’s ranking for that term does not produce quality content. The practice of keyword stuffing is one of the Black Hat tactics that led to external linking becoming such an important factor in search engine results rankings. These external links are far more difficult to control than such things as keyword stuffing, cloaking, etc. This is a great way to get your site “black listed” on search engines too.