Thompson was not saying the devs are incompetent. The dichotomy he made was that either the devs are incompetent or there is something else going on, and then

Thompson was not saying the devs are incompetent. The dichotomy he made was that either the devs are incompetent or there is something else going on, and then proceeds to delineate what that "something else" is. And while he doesn't explicitly state which he thinks is true, the premise of the article is that it is the latter.