I assume the author is referring to the developer experience of their customers (it looks like they sell a developer tool of sorts) rather than their employees. i.e. developer experience is customer experience in this case, and "UX" is referring to the customer's end-users.

Reading that made me not want to read the rest of the article. I'm glad that they realized it was wrong and admitted that, but still, how much stock can we really put in their judgement if that's a realization they had to make?