The document discusses why agile software development works better than traditional predictive methods. It argues that software development is a creative process that is difficult to plan and predict due to variability from factors like changing requirements, people's availability and performance. This variability can lead to queues and delays if not managed properly. Agile methods help manage this variability through techniques like limiting work in progress, reducing task size, and accepting changes in priorities. The document emphasizes that agile is more about adapting processes and putting people first rather than following practices rigidly.