This article misses the biggest reason estimates are important: to make decisions between projects and approaches. Prioritization function is impact/effort. If

This article misses the biggest reason estimates are important: to make decisions between projects and approaches. Prioritization function is impact/effort. If you have Approach A for which you estimate 10 person-weeks, and Approach B for which you estimate 50 person-weeks, you should pick Approach A. Real time estimates, rather than abstract story points, are necessary to calibrate your future estimates, by measuring how over-optimistic you were with past projects.