"Great post" right back at you, kidder!
The old SEO mindset was that you could succeed with tweaks you created yourself, on-page or on-site. Then Google came along and links went to the big stage. Still, many worked as if they could succeed just by building their own network.
Today even the darkest of spammers knows that they need links from elsewhere - and so we have parasite hosted links, spam blogs, and a host of other ills. The fact is that SEO is an integral part of a total business plan. It's INTEGRAL, meaning you can't just isolate some technical factors and work only on them to pop a successful website for organic search.
Do you need to pay attention to on-page factors? Definitely. Is that all there is to SEO? Not by a long shot.