On many occasions “difficult to explain” turns out to be a hint for “not actually true”.
Is this actually an useful heuristic? It seems to me that most things in the world are very difficult to explain truthfully, but especially this case.
We can probably agree that wearing a puffy shirt would be a bad idea, but can anyone really easily explain why?
Perhaps someone could explain why some specific item of clothing is not fashionable, and I am at fault to some extent here, because I have not studied the psychology of fashion in enough depth to eloquently explain this. I am not aware of many people who have attempted to explain specific fashions in a manner that could withstand rational analysis, however.
In earlier centuries, costume rules were a matter not merely of following fashion but of obeying the law of the land. No knight under the rank of lord was permitted to wear a tunic that failed to cover his buttocks.
If the explanation for the original point was: “You can’t wear t-shirts with slogans because the King has decreed it against the law”, would that be a much more satisfying answer? If so, then the answer you’re looking for is that these days fashion is slightly more democratic, but the rules of costume are still mainly decreed by the people with the highest social status, and they have judged t-shirts with slogans on them unfashionable for anyone below a specific rank.
There are better explanations for fashion certainly, but those require intricate knowledge of immensely complex systems, with the system in this case being the synergistic combination of all human animals—all of human society. It is only my opinion, and someone could easily prove me wrong by doing it, but it seems to me that truly explaining a particular fashion in a holistic sense would be a task that well deserves the description — “difficult”.
Desmond Morris writes well about the subject in his book “Peoplewatching”. I found it to be one of the better written and argued writings in the field.
Johnny Depp can wear a puffy shirt because he is the king. The rest of us are probably better off saving our puffy shirts for Halloween.
But yes, what you say is true. If you are awesome enough, you can wear a rationalist slogan t-shirt and make it work.