Exactly. I see many comments here about hidden text, switching user agent, css and bunch of things that don't work anymore. The reason why we used to use that stuff was because Google used to read the whole page and use Keyword Density as one of the many ranking factors. Since those factors aren't used anymore and you can also get penalized, there's no reason to do it. Unless you want a page with just one picture and no text, but still get the benefit of the content, there's no reason to do it.
