You're right, about being a "mixed bag" but Japanese do it better than the regulars. Americans DID NOT started it. It was either in Europe or Asia.
I wouldn't say they do it better. It is fair to say they do it more, but it has gotten a lot bigger here in the States. It did start here.....look at movies or shows back in the 60s and previous. Sure it was not what it is today, but that is what is up. Kunimitsu Takahashi came up with the more modern techniques that basically started the sport.
Edit: No reason to further this debate. We can agree to disagree.