Other commenters are brushing this advice aside on the grounds that it’s isn’t universally applicable. But, if we accept that it requires some discernment, I think it’s pretty sound, particularly in cases where it’s important to be authoritative. I’m reminded of the English crown’s unofficial motto: “don’t complain; don’t explain”.
It conflates exposing your reasoning with being open to debate. I can perfectly well state my decision, make it clear that it's final, while also explaining it. This, for example, is exactly how courts work. I agree with some others here: this advice is not useful often enough to go unqualified. It may make sense to frame it more in terms of "In situations where there the person is unknown and the communication is un…
Like you, I suspect that 99% of my daily interactions would be degraded if I applied this rule. However, the remaining 1% happen to cause the most pain, and it’s precisely here that the articles advice rings true.