When I started promoting websites back in the late 1990’s there were no quality resources online that gave out consistently good advice, and many scams that offered to submit your website to 10,000 search engines for $39.99 which did more harm than good.
Thankfully the automated search engine marketing scam market has mostly been replaced by ethical online marketers, and there are dozens of excellent SEO bloggers who freely give good information to any visitor (ahem such as Netpaths)
SEO went mainstream a long time ago, and it is interesting to see the active participants today. There are 863 million web pages that mention SEO, with 2.4 million searches related to SEO done in the United States each month. There is a lot of interest in getting free traffic to your website, and for many people the allure of having a self sustaining business that runs without assistance is the holy grail of business (and is like a unicorn which does not exist).
Below is a well crafted infographic that shows the statistics of SEO