37signals decided to discontinue their affiliate program due to changes in their business strategy and focus. The company, known for products like Basecamp, felt that affiliate marketing was not a sustainable or effective channel for growth. They wanted to prioritize building direct relationships with their customers rather than relying on affiliates to drive sales. 37signals also wanted to avoid the complexities and costs that come with managing an affiliate program. This decision was part of their broader effort to simplify their operations and focus on long-term customer satisfaction and product development.