Earlier quoted context omitted.
That advice might be feasible for the average HN reader, but what about the average person? How resistant do you think they will be against a social engineering attack telling them to disable code signing?
So let them install that malware and have their data stolen despite all warnings because they deserve it? We can't have safety nets everywhere, and we, in fact, don't. We allow everyone to drive, use knives and handle all kinds of potentially dangerous stuff every day, but for some reason can't trust them with their own phones. Some mistakes are costly, but people learn from them. Such is life.
Can you get social engineered into crashing a car or stabbing yourself? The difference here is that people most likely know the consequences of their actions, unlike with phones/computers where the consequences are nebulous.