Stuffing keyword phrases into your code or in the content is tempting when trying to game the search results, yet does little to enhance the user’s experience. Any keyword usage on a page, whether it’s visible or hidden in the code, needs to have a distinguishable purpose, other than to achieve top rankings.
I’m amazed that people still do this, but keyword stuffing is still common practice by site owners and SEOs that learned a bad practice some time ago and never really unlearned it. Those that keyword stuff really don’t know much about true, results oriented SEO. Aside from the meta keywords tag, you’ll often find keyword stuffing in the alts, descriptions, comments, and often as “hidden” text that the user does not see.
Regardless of how it is employed, keyword stuffing is a practice that is more likely to hurt than help you. The concept of achieving a certain keyword density is really no longer a factor to the algorithms. It’s no longer about how many times you use a word on a page, it’s about how your words are used.