Try to imagine butchering a buffalo with stone tools.
I don’t know if they had them but obsidian shards can be as sharp as glass.
Skinning an elk one year, my boy asked if we could use stone tools. I am nowhere near a knapper, but I can whack an obsidian nodule with a rock. I got a wedge knocked off and it was ridiculously sharp, sharper than any steel blade dreamed of being. Skinning the elk was a breeze, except a little too much pressure would make a slice through the hide without knowing it. A steel blade will give feedback that you are hitting hide now, obsidian will simply cut on through.
They have used obsidian blades for eye surgery.