Hello Sean,
In another MythBusters episode they were asked to try and figure out whether there was any practical benefit to arrows with flint tips vs. simply being sharpened, and their results were surprisingly ambiguous. The flint tipped arrows seemed to penetrate slightly better, but this didn't seem offset by the greatly increased labor to make them. Clearly, stone-tipped weapons were preferred over normal ones if archaeological evidence is any indication, but I'd really like to know why. Stone tools makes complete sense (and therefore hatchets as well), but why add a stone tip to something ostensibly disposable like an arrow unless it provides a substantial benefit in terms of the likelihood that a kill will be successful?
After the tip get in the animal, it breaks off, grinds up and does more damage as the animal runs away. Even modern razor edged arrows kill by bleeding the animal out.
