The technology we have available today allows us to massively automate many tasks that had to be manually done only a few years ago. This has reduced the level of technical ability required for people do things like build their own websites, set up landing pages and build lists of subscribers. You can literally build a website within minutes today, even if you have zero technical computer skills.
Affiliate marketing is also called "performance marketing", in reference to how sales employees are typically being compensated. Such employees are typically paid a commission for each sale they close, and sometimes are paid performance incentives for exceeding objectives. Affiliates are not employed by the advertiser whose products or services they promote, but the compensation models applied to affiliate marketing are very similar to the ones used for people in the advertisers' internal sales department.