SEO isn't what it used to be. I'd argue that the term "SEO" is barely even still relevant.
SEO used to be a powerful tool. (Powerful is an understatement.) One could easily game the system. You could buy links, submit to link wheels and directory blasts, keyword stuff, and hide on-page text. You could submit to irrelevant blogs for keyword-rich anchor text, and you could syndicate your content across the Web. Those were all viable techniques during the SEO heyday, techniques that brought thousands of visitors to sites that were undeserving.
Those tactics didn't bring value to the customer, however, and were generally bad for the business world.
Today, each of those tactics is unhelpful. Yes, you can guest-blog... but only occasionally and in very specific instances. Yes, you can syndicate articles... but only with canonical tags or other methods that prove to be difficult to execute because of restrictions from the destination site. You cannot buy links, use link schemes, use directory blasts or any hidden content tactics, or you will be hit by an algorithmic or manual penalty faster than you can say, "What's Google's algorithm?"
SEO isn't dead; it's just different. I like to compare the current state of the industry to a teenager. We (the parents) are mad because our child is acting strange. Our beloved child, SEO, is growing up into someone we don't even know or understand anymore. Our teen is now a fickle semi-adult with mood swings every other month (Google Authorship, anyone?). SEO has evolved as Google has evolved, and it's now more of an aggregate result of other marketing tasks than as its own standalone task.
Confused? You should be. Everyone is. Why are there still entire companies based around SEO if it hardly has its own space in the online marketing realm? Why are we still even talking about it?
You could say we're talking about SEO because some of it still needs to be done: basic on-page optimization; technical stuff, such as sitemaps, redirects, and making sure robots are active; and maybe some link-profile cleaning. However, I'd then counter that almost anyone can do that stuff now. Between easy-to-use WordPress plugins, YouTube tutorials, and sites like this one, anyone can learn, share, and execute the basics by themselves.