Much of this is steeped in buyer psychology. The best marketers in the world know that there is a psychological process that must occur for prospects to whip out those credit cards and turn into buyers or even hyper-active buyers. One such person whose perfected this process is Russell Brunson, an "underground entrepreneur" who founded a company called ClickFunnels, a sales funnel SaaS business that empowers marketers from around the world to build marketing automation without all the hassle.
The messaging on the page reinforces the reason for their click, reducing or removing confusion and therefore increasing conversion rates. This improves overall user experience and reduces the bounce rate (individuals leaving the site without converting or navigating to another portion of the site) for the page. Good message matching can increase conversion by up to 50% in many cases. However, what Brunson cleverly conceived with ClickFunnels is to create a SaaS that can integrate with the world's most popular platforms and virtually anyone can quietly launch a funnel in hours as opposed to weeks of hefty coding and programming. As a fervent user of ClickFunnels myself, I can tell you that the system is impressive beyond measure.