You make some valid points. However, the statement above is a critical consideration that FAR TOO MANY hunters fail to understand...
As I have said many times, too many hunters fall for the marketing whether it is in the form of fast bows or huge cutting diameter mechanicals promising huge holes and rivers of blood! That's the more likely reason the majority of those broadheads in Scott's photo are mechanicals...
In my experience of setting up hunting bows for hundreds of hunters over last 2 decades, the majority of bowhunters DO NOT shoot set-ups that are capable of producing the amount of momentum necessary for the proper deployment of the vast majority of these mechanical broadhead designs. Yet, as you alluded to, they are very popular... Far too many bowhunters simply screw on a broadhead that they bought for no other reason that the marketing hype and go hunting without any field testing or regard as to the limitations of their own personal set-ups...
Another point you make that I agree with is that these designs are not effective on large bones... I would take it even farther by saying they aren't really designed to penetrate any bones. By design, most mechanical designs often break, bend, and deflect when they contact even rib bones. Even perfectly placed shots with powerful set-ups result in the broadhead emerging mangled most of the time... It's difficult enough to make a lethally placed shot without all of the other variables that contribute to failure... My view, and the advice I give to my clients is why even take the chance with a known avoidable variable...?
Two of my all-time favorite memes...