Rather than merely echo Peter's reply, I thought I might point anyone who is interested to a fine piece of scholarship that addresses that notion in a fairly rigorous and sometimes surprising manner:
To that, I would only add that while the concept of "michi" or "do" has a long provenance, the opening of those arts to broader social circles, while not entirely unknown, particularly during the very late Tokugawa era, didn't really become a mass phenomenon until the Meiji era, and both functional and conceptual change are associated with that opening.
Hope this helps.
Have you looked at her other work, entitled Bonds of Civility
? I think she focuses more generally on the arts that were opened to the broader social circles, all of which I suspect involved mastering 'forms', as exemplified by those with 'true' understanding. (Chapter 12, entitled, "Hierarchical Civility and Beauty: Etiquette and Manners in Tokugawa Manuals," presents some intriguing evidence of this.) She focuses on the so-called za
(= sitting) arts, but I think the link with martial arts is not so distant.
The other issue for me is that of invented tradition and this is connected with the question of 'true' understanding. If you remove this word from the title of the thread, it becomes a no-brainer. Of course, one can understand budo without training in Japan, but what does 'true' understanding add?