Google search was actually great between the period where pagerank successfully defeated old-school SEO tactics and banner advertising starting earning enough that the "bloggers" could pay cheap writers to pad their articles in convincing ways.
2006 was the first year I remember paid blog posts appearing from content farms that would exist only to increase your inbound links and page rank. Those days companies were paying cents per post to get their sites to #1 in Google while Google just wagged their finger and said "naughty, naughty."
First decade of the 2000's if I had to guess.