Agile practices only make sense when iteration is cheap

As hardware costs collapsed (Moore's law), the cost equation flipped: people became expensive relative to computing. Instead of minimizing machine cycles, we now minimize time-to-learning and maximize human creativity.

Agile practices like continuous integration, test-driven development, and rapid prototyping only make sense when iteration is cheap. They would have been economic insanity in the punch card era.

On the other hand, Slow feedback loops and expensive computing forced optimization for machines over people.