Not to denigrate the Stone Age. There are artisans out there who sell Obsidian Blade knives right now. Some have been found that are thousands of years old and still sharp. Steel cant make that claim.
There are doctors who use obsidian blades in operations. They sterilize just as well as steel, do not lose their edge, and in fact, are sharper. For small incisions, they leave much smaller scars.