It’s especially popular in Silicon Valley. Quite possibly, places like Reddit and Hacker News, are training for the required level of intellectual smugness, and certitude that you can dismiss every annoying argument with a logical fallacy. That sounds smug of me, but I’m actually serious. One of their defects, is that once you memorize all the fallacies (“Appeal to authority,” “Ad hominem,”) you can easily reach the…
A contradiction creates a structural fallacy; if you find one, it's a fair belief that at least one of the supporting claims is false. In contrast, appeal to authority is probabilistic: we don't know, given the current context, if the authority is right, so they might be wrong... But we don't have time to read the universe into this situation so an appeal to authority is better than nothing.
... and this observation should be coupled with the observation that the school of rhetoric wasn't teaching a method for finding truth; it was teaching a method for beating an opponent in a legal argument. "Appeal to authority is a logical fallacy" is a great sword to bring to bear if your goal is to turn off the audience's ability to ask whether we should give the word of the environmental scientist and the washed-up TV actor equal weight on the topic of environmental science...