One common misconception of Agile is that it simply allows you to get everything done faster. This is simply not true. Agile allows us to plan a much smaller scope of work, delivering iteratively and incrementally to deliver the least amount scope needed to solve the problem/capture the opportunity. The speed comes from only delivering what the customer needed. This is in contrast to how we used to scope a release when we delivered everything we thought they might want.
This is stakeholder debt. I define stakeholder debt as the difference between everything they scoped for the release, minus what the customer uses.