I wonder if all historical analysis about Okinawa should be set aside until a translation of the Okinawan Karate Encyclopedia is available. In most historical issues I think if the Okinawan's haven't addressed it, there is no chance of finding a historical answer which then only leaves logic and not proof.
It is a certainty that there is no serious Chinese arts that Karate resembles enough to make a direct parallel. If that existed I rather suspect the Chinese would really enjoy showing the true history.
Off hand I think the strongest logic is that various Chinese sources 'inspired' the Okinawan creators, both from the Okinawan Chinese villages and mainland forays over time.
Another logical answer actually given by the Chinese years ago in the now defunct O'Neil's karate magazine from England proposed the answer is the Chinese instructors were not really aligned with the more serious National arts, and those systems died with the instructors. They then hastened to add that doesn't mean they were bad, just didn't last.
Frankly it may also be:
1. Nobody trained long enough to really get the source system (Some Chinese systems require several decades of study). or
2. The Okinawans really weren't very good students and simply forgot things and changed the results in turn.
I see this as a 'proof' that logic gives us very little.
If you can use logic to make your own practice more poweful, good, but one's personal acceptance rarely sways others who use a different logic chain.
I focus on what I do and how to make it better for my students, seems enough.
bushi no te isshinryu
offering free instruction for 30 years