What is a good engine?

Users and programmers rarely understand each other. They seem to speak different languages. They are like two camps, despising each other but united against a common enemy in the face of the project being implemented. Technical tasks, prototypes and project managers and even DAO programming only smooth sharp corners, while the gap between the warring camps continues to grow.
The reasons for this have long been known - the user looks at the product from the interface. For him, a good engine is a convenient GUI, which allows you to easily perform the required actions, and a nice appearance. For a programmer, the same engine is primarily source code, architecture, documentation, and extensibility.
Now, armed with these facts, let's see what happens in our runet. And we have nothing less than that - a holy war for increasing usability. Web sites are being lynched, companies produce boxed CMS with convenient admin and user documentation. And all this is of course great and wonderful.