What do you mean?
There are several places where the author has created mockups of how they think some data would look if it were collected.
Oh, you mean like, I dunno, actually measuring them!?
You seem to have misheard "this is excessive extrapolation from too little hard data" as "the general phenomenon doesn't exist".
> 1000s of data points are evidence
Except they're the same kind my neighbor uses when he says that kids these days are different and don't respect their elders like they used-to.