Pearl Drums: agreed, I understand your point completely. That's why I would put you squarely in the "first" school of thought mentioned above, and I really mean no offense by that, it's just a way to show a difference. If I had to guess I would say that folks in that first school of thought come from an engineering or maybe a mathematics background where things are expected and required to be "right or wrong". That's a great thing, we need that sort of thinking.
Now, to counter your argument though, I would suggest that I don't think it was all that difficult to carve out a bow for native folk. Mainly because I don't think they concerned themselves with making one to last forever and not fail. If it were me and I had to feed my family with a bow, I'd make 3 or 4 bows, and take them all with me, and also be on the lookout for a gun. And, I would be in the know on how to make a new bow, in the field, with minimal equipment, as fast as I could, that would get the job done. This would lead me to believe that there was a "right enough, although not perfect" school of thought, which I fall squarely in the middle of myself. I'm of the opinion that an "early bowyer" (to use the term created earlier) could probably throw together a functional weapon in a day or so if they really had to. And I suspect they really had to, cause things happen and bows get broke and you'd have to be able to replace one on the fly so that you could catch back up with the herd. I would surmise that the differences in design that we see today in our history books were born out of necessity or lack of time back then - not because the person didn't know any better, but because they DID know what the bow could do, and they choose specifically to do the least amount of work to create a working weapon that did the job. That would lead to my assumption that the did the most practical thing at the time, and worried about the other stuff when they had time or reason to worry about it - say for ceremonial purposes or in the making of a weapon for a higher ranking warrior or chief.