People have to find it before they can come to it, so SEO matters.
Also, what do you mean, built to rank? Low quality content with a lot of SEO effort? That was always a short term plan. High quality content in the hope of ranking without a lot of SEO? It used to work.
IN fact looking at some of the high ranking content farms, I think the a route to success now is to be big, have non-spam (not high quality, just minimal quality) content, and excellent SEO>