A division of labour doesn't have to mean a division of expertise.
Are you trying to say that products wouldn't be better if everyone involved in the process was more skilled in the techniques of the others?
The distinction is entirely a bogus one which has more to offer the corporate org chart and payroll rather than the ends of good design and products.
i'm answering the question of 'how much coding do you need to learn to design websites?'
and clearly the answer is 'none'.
of course, cross-knowledge is preferable when working on a project with different disciplines.
