Could it be that Dr. Purdom limits her research to avoid a conflict with her religious belief? She seems to want to stop at a point where an untrained audience might get the impression that point mutations stall at the micro-evolutionary stage. She would thus, knowingly or not, be building a platform to refute macro-evolution that would appeal to the untrained audience. I am speaking from the position of a non-professional listener.
It is one of the commonest of mistakes to consider that the limit of our power of perception is also the limit of all there is to perceive. C. W. Leadbeater
Thanks, Percy, for the Vitamin C example. That seems simple and reasonable to me.
"Anyone who has the power to make you believe absurdities has the power to make you commit injustices."
Voltaire