Yep, that is what the listeners say via their behaviour... signals below the
strength I mentioned are more subject to noise, harder to tune, etc. So they
don't listen.


No I disagree. It must be content not the ability to get a noise free
signal. So it looks like you never made it up here.

Of course they listen to whatever station has the content they want but
it must also have a good signal. If either criteria is lacking, they
find another outlet or give up. That's the behavior of the vast majority
of AM listeners. They are the ones that create the ratings which are
reflected in the diaries. The fact that MW Dx'ers don't like this
reality, including myself, is unfortunately irrelevant.