I've got a long history here, stretching all the way back to 2007. At that time 80% of my traffic was organic, and most importantly, was spread equally between MSN, Yahoo, Google, AOL, etc. I paid for ad's through HotScripts, and this was a solid source of leads. This mixture, along with a fast, secure, easy to use site and great word of mouth lead to an annual growth rate of around 30%, ending up in 2011 with a mont…
Google at least has the organic option. "If your content is fresh and linked to from reputable sites, we'll promote you in the search results... for free." Facebook is purely pay-for-play. Paying for boosted posts is the only way to cut through the noise (unless your content goes organically viral, which only has a 24 hr shelf life).
Some evolution images and stories: http://searchengineland.com/evolution-google-serps-three-key...
It is still "free" but takes a lot of work to get there, and it is worth less than it used to be. Lots of SEO's have gone the way of paid.