the criticism of argument from authority is really only valid for logic-based arguments (which only exist in math). In nearly every argument online, the topic is not logic-based, but more a combination of fuzzy reason and rhetoric. In such situations, we normally allow for some prior belief that people who obtained education and have worked in an area have some level of expertise that makes their arguments carry more weight. While you can argue whether this makes sense, it certainly seems reasonable to me- although I still apply skepticism to expert opinions.