While I agree with this article, we also need to take into account whether SEO types are actually benefiting their website or not.
Yes, there are spammers all across the web, and Google have effectively created an entire industry of idiots spamming the web, chanting "content is king". However, I'm willing to bet that 90-95% of all SEO work done by ANYONE is largely a wasted effort.
My reasons for believing this is my first-hand experience on this forum, and in the wide world of SEO. The sheer amount of crap I've read and heard from people that take blogs from nobodies as gospel, and the level on inaccurate or largely dated information coming from cheap SEO sweat shops in India makes me largely believe that any benefits these SEO analysts actually get are a natural effect of the web at large.
They are much like rain dancers. They dance in the sun all day, and when it rains they claim success. They tell others that if you dance in a certain way that they can make rain too. These idiots will then copy the first dancer, and when it rains again the cycle continues.
Google's search algorithm is a black box, and anyone with even half a brain would realise that trying to decipher a complicated algorithm behind a black box is a near impossible feat. The only real thing to know about SEO is to do your own research, and to lay the groundwork for a successful website. Anyone with any knowledge of machine learning or web parsing will know that no computer can read a web page and know 100% that content is "good". Google runs from back-links, and over time Google has become very good at sifting through SEO spam and genuine quality. It's why we see so many people on here complaining about the "panda update".
In my mind, the smart people continue to do the same thing they've always done. They treat SEO as a subset of a successful online marketing campaign, and build a brand. What we experience is the aftermath of a bunch of rain dancers thinking they can make it rain.