Alastair, I often present this image to my students and ask how many of them have seen the image that tries to explain UX in a simple visual way.

Many happily put up their hand… I then proceed to enlighten them about how this is oversimplification without considering that even if the path was where the mud path is, user’s might actually take a different route. I also explain how the mud path has been worn down with use, but we don’t have a clear way of understanding the amount of use the paved path actually has in comparison.

User’s will give us data to inform decisions, but jumping to conclusions on a fraction of the data can be so dangerous…

Just my way of saying I agree :P