Incorrect! There's LOTS of factual historical accounts in plenty of books on the market, found in museums, forts, and libraries and there's plenty of resources abound.
Just as you re-create your ancestor's dances and lore, we re-create the lore that has been passed down to us. It's just done in different ways, but the ends are the same.
Some go all out as you do and follow literally everything 'by the book', (course that depends on what book...), and there are others who simply want to have fun and do so.
That's why Renaissance Faires and Pirate Faires throughout areas of the USA exist. If there was no interest there wouldn't be anyone.
There is certianly an interest in Indian Pow-Wows, well it's the same with us.