Some search engine positive and negative ranking factors mentioned in the website are still valid for Search Engine Optimization and not just all myths. That is not to say that there are not many Seo Myths or old practices preached around.
Some of the recommendations included in that website are also contained in Jill’s beautiful Nitty-gritty SEO guide. If no factor or recommendation can be considered valid for SEO and all factors included in the listing have to be considered just myths, why should people pay SEO companies for and why do SEO companies exist?
As you said, search engine ranking algorithms will change all the time and what is valid today might not be tomorrow. I still think that the listing can be a good starting point to understand what may be good and what may be bad for improving rankings, what may be short-sighted Black Hat SEO practices and what may be long-term SE-friendly optimization practices.
Of course, SEO is not a precise Science, everyhing is relative and no definitive formula can be applied to a website to guarantee high rankings but, I am still convinced that there must be some general accepted recommendations and factors to consider when designing a website.