ok I think about this alot,, not saying what I think is right at all, but very fun to speculate,,
the height of the archer could have something to do with the size of bow,, but thats just part of it,,
I really think the performance was one of the main factors,,,
even the short bow,,
the longer bows were that were not backed probably did best in humid conditions,, just like the bows from South America
if you get a bow to draw say 24 inches,, thats a pretty effective power stroke, and good cast can be obtained in a 48 or 50 inch bow,,if sinew backed ,,,
a self bow slightly longer will shoot well at 24 inches of draw,,
some bows were shorter and had a shorter power stroke, but at a higher poundage still effective,, on game or for war,,
I have been making bows for 30 years and they are more simple and Native like in design as I learn more and gain experience,,
I have a very short 42 inches sinew backed bow, its about 50#@ 20 inches,,
it will shoot a 500 grain arrow about 140fps,, ok thats slow compared to a good long draw self bow,, but 140 fps is 140fps,,
its so short it would almost go in a back quiver,
it is accurate for close shots,, and would make a nice hunting bow no matter how tall your were,,,
if you need more fps,, you could go up in weight to achieve more cast,, say for Buffalo or large game,, so I can see why and how some archers used the short bows effectively for hunting and war,, maybe like today,,, alot was personal preference as well,,based on what the archer liked??