What is the primary purpose of having both WCAG guidelines and techniques?

The primary purpose of having both WCAG guidelines and techniques is to enable updates as technology evolves. WCAG guidelines establish broad, principles-based goals for accessibility that are applicable regardless of the technology in use. These guidelines are designed to be somewhat static, providing a foundation for what accessibility means across all digital content.

On the other hand, the techniques associated with these guidelines serve as practical implementations that can change and adapt with advancements in technology. As new technologies and methodologies emerge, the techniques can be modified or updated to ensure that the overarching goals of the guidelines continue to be met. This dynamic aspect allows web content to remain accessible as the digital landscape evolves.

While flexibility in interpretation, defining legal requirements, and promoting usability are interesting considerations, they do not capture the essential reason why both guidelines and techniques are needed in the context of maintaining up-to-date and effective accessibility standards. The goal of WCAG is to create a sustainable and relevant framework for accessibility that can respond to the rapid growth and change seen in technology.