By treating even small functions like a black box it promotes separation of concerns and allows said black box to evolve independently.

The elimination of what is arguably the biggest monoculture in the history of software development would mean that we, the community, could finally take charge of both languages and run-times, and start to iterate and grow these independently of browser/server platforms, vendors, and organizations, all pulling in different directions, struggling for control of standards, and (perhaps most importantly) freeing the entire community of developers from the group pressure of One Language To Rule Them All.