If I remember correctly, Joe did pull 210lbs with his yew warbow + resistance rubber band.
I think technique is a good explanation, why some skinny bois can pull 100lbs.
And on the other hand, there are just pure power dudes who have no technique at all and can pull 100lbs.
And on top of that, it depends on the draw lenght of the bow. A warbow tillered to 150lbs at 30'' feels a lot heavier than 150lbs tillered to 32''.
And if it has set or reflex makes difference too. Shooting reflexed warbow is a lot more difficult.
Once you get (at least for me) past certain point of the draw, you can start to use your back muscles to pull the bow=it gets easier.
For me the limiting factor is the feeling my left arm's elbow is going to be crushed.
I have been training to shoot warbows for two years and I can barely pull 150lbs at 30''.
So based on that, some people are more gifted with war bows than others.
And I don't really know what is the limit on what is the absolute highest poundage one can pull. Meybe the point where your bones start snapping from left arm? lol
I am not stating any of these things as an absolute truth, just my experiences and information from others and internet.