"implementation under the hood requires a lot of work" "people don't make functionally identical clones" "massive refactoring to allow for extensibility" You

"implementation under the hood requires a lot of work" "people don't make functionally identical clones" "massive refactoring to allow for extensibility" You're enumerating the factors that make my point true. Those are some of the reasons why building software takes a lot even if you know exactly what it is supposed to do. You can compound that to the problem of figuring out what the software should do, which classic IDEs are also bad at. Online collaboration and prototyping tools that put the program in front of stakeholders early; they're like car makers' focus groups that were used to design cars tailored to a target demographic group.