Because a thing that is 80 percent done and in the hands of the person it was made for teaches you more in a week than a perfect version teaches you in a year; the perfect version never leaves your desk. A planning tool for a family business and a tool that turns a quote into a PDF were not top creations, but customers felt heard and their feedback gave direction. My statistics tool went live with a first bot classifier and was at version nine two weeks later, every rule calibrated on real logs. One exception: 80 percent is not an excuse for sloppy foundations. The backend stays hard; the pages, tools and words on top may be 80 today and 90 next week.