Marcus Herrmann discusses the Pareto principle, also known as the 80-20 rule, and how it applies to web accessibility. He argues that 80% of accessibility issues can be addressed with 20% of the effort, while the remaining 20% require significantly more work.

The overall message is that web accessibility should not be seen as an overwhelming or daunting task. By focusing on the 80% of easily addressable issues, organizations can make significant progress in improving the accessibility of their digital interfaces. He encourages readers to tackle the low-hanging fruit without being discouraged by the remaining 20% of more complex challenges.