that's maybe an exaggeration; people still make buildings out of flint, they make it into perfect spheres for ball mills, and when flintlock was the firing mechanism of choice, they shaped flints for rifles out of it. the main reason we don't have a lot of flint goods around is that, aside from its edge-forming powers, it doesn't have great properties: it's brittle, nonconductive and not all that pretty, much like unglazed fired clay

you can grind it into whatever shape you want if you're careful about silicosis

The ground is covered with flint arrowheads in various parts of TX that I’ve visited and/or inhabited. It’s really hard for me to imagine Indians crafting so many of them if it were that hard to work with.