This is what I would bet on. If you spent decades of your life knapping various "easy" and ideal stones for tools and getting quite skilled at it, it doesn't seem like much of a stretch for them to try knapping a "difficult" stone just because it looks cooler and you can show it off.

Exactly. Same reason kids and people today are drawn to it and gems in general. Even today, people imbue crystals with mystical properties.

Good job neither the article nor the backing paper discussed made any such definite claim.

Perhaps you're confusing

  "which *may* have had symbolic or ritual significance."

with "absolutely had to do with (a) religion" ?

Attribution of potential cause of inferred behaviour to "ritual" is a long standing practice in archaeology; it's code for "we don't know" and covers all manner of things that may simply have developed as habit over years, may have unknown and non supernatural causes / motivations, etc.