I'm definitely one of those strictly-programming people.
Sure, I can probably hack together a sorta-kinda technically-usable UI, but I know I'm awful at it. In my professional life I quite early on realized any attempt on my side is just a waste of time and effort, so these days as a mostly-backend developer I don't go beyond sticking bare unstyled HTML elements on a page to demonstrate basic functionality. I'll leave all the design stuff to the people who are actually good at it!