Before SEO was invented, we called it "website promotion". In the year 2000, I worked full time as a user interface engineer and moonlighted at night doing search engine marketing work and my blog, and in that same year I was trained in human factors by my employer. That was when I fell in love with UX and began Holistic SEO and UX work, discussions, and promoting the union of those two opposing (especially in those days), fields.
Years later, as links became the method for marketing, one of my clients was paying a well known marketing company $10,000 for them to find him links that they would purchase for an additional several thousand per link. We would argue all the time about how his websites weren't user friendly, but he was paying out the whazoo for links. While I was hired to redesign all of his sites, he refused to follow some of my recommendations. His sites were invasive and strictly marketing oriented, with no desire to actually connect with the humans coming to them.
I got to thinking today about all the companies who paid enormous amounts of money to buy links, even after the crack downs against the practice. I was never able to see how what they were doing was an investment that would benefit them for the long term. To me, the benefit was for the search engine marketing company that was hired.
I was thinking today about this and wondered if the companies that broke their piggy banks to buy links are glad they did.