A very simple answer: users do not know that they want classic desktop systems, where the OS was a single application and apps was just bits of code inside it.

A very simple answer: users do not know that they want classic desktop systems, where the OS was a single application and apps was just bits of code inside it. Let's take modern Emacs as an example. Unfortunately most modern devs do not know that as well. People lost the concept of working in a live framework where pushing just few bit of code suffice to bend their environment. You can automate Emacs without knowing much of it, and without any specific DSL or limited interface for scripting. That's the point that fusion both views, the devs with the full sources and build process vs the users and a specific live instance of a program. Please try to rediscover such classic tech, because that's anyway the future, those who understand it now are just 10+ years in the future.