So in a sense it is self limiting to a degree, discovering this limit is when the pilot realises that his increased pitchup rate does not give more TRT for increased energy input, it just funds an increased Cd
When you reread your Prouty you will see that the pitchup does increase Cd but, due to the inflow angle, that increase in drag actually increases Nr - just like the driving force in autorotation. It's called flare effect.