I don't think it has to be that complex. Here in the Netherlands, we have a system that non-luxury houses get points and the number of points determines the maximum rent.
It's not perfect, but for many decades it worked quite well.
A reform is now being proposed to extend the system to middle class housing.
Complex and subjective systems are risky, precisely because they provide opportunities to cheat.
Simple is best.
Honestly, she deserves credit for even showing the yellow line.
And to also show the whole right side of the graph.
She really could have cropped the picture differently to give it a spin, but she's being honest.