Both? I can imagine someone looking at the graph showing a decrease of affordable homes sold over time and wondering if they will soon be on the other side of the line.
Of course that’s true. The question is whether its actual incentive is anything like the one you’ve surmised and used in your critique. I think that your take seems strained and that the actual incentive is likely more sophisticated in general and intuitively biases in the opposite direction if in any relation to your point at all.