This key distinction they're trying to make in this articles isn't about UX, but rather "UX developer". My understanding of UX is knowing the users & market and

This key distinction they're trying to make in this articles isn't about UX, but rather "UX developer". My understanding of UX is knowing the users & market and producing a flow. The key benefit of a UX developer is the prototype and product are one and the same, and are created with useable code rather than mock-ups. This allows refinement and iteration all the way through production. We're not so focused on UI, because that's easy to create with static mock-ups. UX development takes the next step to determine how the different static UIs work with actual code and users. A key difference between UX dev and UI dev: the UX dev won't worry about skins and other design parts. It's more about the layout, functionality, and ease of use. Once that's worked out, a designer can make it clean.