I think that in many cases, Saxon dressers have internalized their rules (having grown up with them) and don't really see them as rules, just "what's done". Having someone inform them what is appropriate for Highland wear just irks.
Perfectly made point. And I think, if I understand them correctly, that many of our native Scots feel the same way about Highland dress. As Jock Scot and MacMillan of Rathdown have pointed out so many times, they have grown up wearing this attire and just naturally know what's 'right' and what's not. It's only when we who didn't grow up in such an environment start asking what the 'rules' are that they have to start writing down these rules.

It would probably be the same if we were on a forum for Saxon style dress, trying to explain the 'rules' of wearing trousers to people who had only worn loin cloths their whole lives.