Excel Changed the world
It can be argued that no piece of software has unlocked more human potential than Microsoft Excel in the 1980's. Prior to the release of Excel, working in digital spreadsheets was the domain of computer scientists. You needed to be highly technical in order to even use a computer let alone use math functions on one.
When excel was introduced, you brought in a whole new class of workers to the fold which introduced an unparalleled technological change in the business world. How many other tools have had such an impact? How much time was saved by allowing this tool to operate a business? How much effort was abstracted away to this system to allow companies to focus elsewhere? The cost of operating certain businesses became cheaper and cheaper as a higher percentage of the population learned how to use these tools. Deflation is an amazing force.