Actually, please re-read the statement:
“But if you want to take full advantage of the online promotional mechanisms at your fingertips, in all but rare cases you should not incorporate SEO into your marketing plan for your business.”

Key thing to note is “rare cases”…let me give you an example. Let’s say you are launching a new product/micro site and are not sure that it will sell well or be viable, you may start and test through various paid direct marketing/advertising outlets (such as PPC) before you optimize the site and build trust factor and visitors through SEO. Since SEO is a long term and ongoing building process, if you are not sure about a product, why would you build your SEO (sometimes may take 12 months+ to build organic visitors), if you might invest a significant amount of resource just to realize the time and money might have been wasted, until you can prove that a product/micro site is viable…anyway, thanks again for your comment!

What? Why would you not do a good job for any website to create great content that is W3C compliant with good url and link structure? (Isn’t this standard good SEO practice or am I missing something?)If nothing else you at least give your visitors a better experience.

I totally agree you would use all forms of other marketing efforts to promote your business/site including offline, but I do not understand why anyone would not just do the right thing and ensure best practice basic SEO principles.