Part of the fun is immersion. A player can easily suspend disbelief if it's important for the game's conceit (it's like our world, but with dragons and magic). But if it's based on a misunderstanding of the base nature of the world, it's just a distraction with no value.
Sometimes it can be fun to get into the medieval mindset and have the rules reinforce their erroneous beliefs (maybe bloodletting is treated as a useful treatment for diseases, for example). But in this case, if the armor types are based on a misunderstanding in the Victorian era, I don't really see the fun in pretending that these other types of armor both exist and would be useful.
Sometimes it can be fun to get into the medieval mindset and have the rules reinforce their erroneous beliefs (maybe bloodletting is treated as a useful treatment for diseases, for example). But in this case, if the armor types are based on a misunderstanding in the Victorian era, I don't really see the fun in pretending that these other types of armor both exist and would be useful.