The idea conveyed here is that scarcity being the foundation of value is a myth. No economist believes that just because something happens to be rare makes it inherently valuable. I dont think any real economist really believes that. I think it was a pop culture, snake oil salesman thing that brought it into the zeitgeist. Yet to this day, the myth still prevails and bitcoin is mostly based on that concept. Just because something is "limited" doesn't mean it already has value.

Scarcity is necessary but not sufficient for something to have value. There are plenty of rare things that are worthless. Various forms of toxic waste, for example, aren't particularly common and have negative value.