There are four ways to build your website traffic (and A Million Tweaks uses all of them):
For most websites the biggest source of traffic is through Google via natural search, so it certainly makes sense to try to get the highest position you can in the search engines for as many relevant keyphrases as you feel entitled to.
But social media is becoming more important. YouTube gets more hits than Google, and YouTube videos are appearing in the first position of Google search.
You need to be where your audience is, saying the right things. We can help, that's what we do.
John Allsopp, Tweaker Extraordinaire