"They" was intended to be the customers: the clients paying for development.
Ime, the less visibility and knowledge customers have into an implementation, the more opportunity there is for developers (especially contract) to go off the rails.
When the code behind "it works in my browser" is completely opaque... that doesn't set up the best technical incentives in the market. Past "minimize time-to-deliver".
You can be a Java dev for years (forever really) without understanding how the JVM works. I don't see why the web has to be any different.