On the Value of SEO
The Principal of Optimizing for Search is Sound
It is methodologically important to take a skeptical approach to the practices of search engine optimization. But the principle strategic purpose of optimizing for high placement in the organic search results is demonstrably valuable, and demonstrably achievable. That is, I am not skeptical of the value of SEO, but of the purported methods of achieving success in it.
In order for SEO to be a valuable pursuit two things must be true. There must be a benefit to possessing high search engine rankings, and you must be able to manipulate the web environment to achieve those rankings.
As to the benefits of high rankings, the short answer is traffic, and the correlation between the two is crystal clear. The higher you rank in the search engines for keywords relevant to your web site, the more traffic you receive. There's no shortage of hard data for this – and it is hard, because the information comes from correlative analytics. Whether or not a website receiving traffic is it itself a benefit is a bit of moot point. For detractors that disparage the "bad" traffic that a search engine can bring, even if stylistically a traffic benefit, consider that there's a "good traffic" segment of search engine users available, even if untapped.
As to the ability to manipulate rankings, there's a multitude of examples – now subsumed under "SEO best practices" – that proves that ability exists. The simplest example is keyword use. A page that lacks the target keyword in its <title> and text will rank more poorly that if it contains it. Or a page will rank better that has text on the page, rather than a page with that text in an image. Or that a site with lots of good links to it will rank better than one that has none. Any number of now standard SEO techniques, however much their precise impact on rankings are undiscoverable, proves that manipulating web sites and their environment can improve rankings.
These two things being demonstrably true, then there is value in the practice of search engine optimization. To those other skeptics that are dismissive of this value, then they either don't accord value to traffic, or don't consider such mundane tasks as formulating <title> tags "SEO." To Jason Calacanis's famous claim that "SEO is bullshit" one can legitimately claim that it's valuable bullshit. Optimization increases rankings, and rankings increase traffic.