^ That's just how cultural transmission works, in Morita's filming style for instance you could already sense a lot of Dan Wolfe influences early on, in general humans start by studying how other people do something before coming up with their own (I find the Japanese in general to be really good at reinterpreting existing phenomenons to the point of making it their own), and during their formative years where they're still sucking up the influences they more often than not wear them on their sleeves yes, because it naturally takes some time for style in everything to mature and shine; one starts with just a few reference points in everything they tackle, then little by little they expand over to the whole picture and better understand what they're trying to do themselves. Later on Yoan literally exported Morita's filming style over to the West, too, starting in Europe but as the Internet was blowing up people as far as in the U.S. really caught up on it, all that shit really is just some transcontinental ping pong game the most passionate players build upon the rules of with every smash.
I guess this very process of progressive discovery also explains the common superficial perception of 'Japanese skateboarding' I was rambling about earlier, but even with a logical reason for the phenomenon I still find it frustrating sometimes seeing how geographical boundaries still affect the spreading of a global culture (but at the same time, it's very interesting to study).