The Agile Manifesto starts with “We have found…” So that’s the why. You can ask for elaboration, or disagree with the results, but the opinion of the signers o

The Agile Manifesto starts with “We have found…” So that’s the why. You can ask for elaboration, or disagree with the results, but the opinion of the signers of the Agile Manifesto, based on their experience, is that to prefer the former over the latter, while acknowledging that the latter principles have value, they tend to succeed (and enjoy their work more) when deciding between the two (there are always trade offs) to give greater weight to the more lightweight, practical, and less rigid values — hence the use of the word “agile”.