It's the lack of qualification of things like an appeal to authority which mostly I think we (ok, I) trip over. But, appeals to authority are both common and useful. It depends.
A similar example might be how people feel about Helen Caldecott, and theories like "radiation hormesis" because you can't both have "no safe limit" and "maybe we've developed biologically in radioactivity, forever since the first eukaryotes emerged" at the same time. One necessarily excludes the other, taken literally. taken figuratively, Sure: we don't know what a safe limit is, except statistically and even that has qualifications.
I particularly like "no true scotsman" because if you follow the reddit /r/scotland you will know the initial propositional question "what is a true scotsman" is pretty vague. We know it excludes a lot of North American ancestry tracers, who are obsessed with lineage, but are most definitely not a true scotsman. But the idea of it being defined as Harry Lauder is a bit .. unacceptable. (of course the test of the true scotsman is how they make porridge)
There's a particular scotsman, the one in full army formal band kilt, playing the bagpipes, who before photoshop appeared in a massive selection of scots scenic postcards, artfully added into the photo of a castle, a hilltop, the lakeside. I think he probably IS a true scotsman.