Great story. Based on the research of Charles Stanish of UCLA's Cotsen Institute, Ebay harms archaeological looting.
In essence, Ebay and the internet in general has made it easier for people around the world to market "fakes"/replicas of archaeological artifacts for low prices. In turn, this has satisfied many customers who want something "authentic" and either prefer replicas due to ethics/costs, or don't know the difference and are simply amazed that an "ancient" Maya bowl markets for $35. This has lessened the demand for actual looted antiquities, and has flooded the market with excellent replicas, making the entire issue of buying and selling the real deal more difficult and risky.
Looting hasn't even remotely gone away. But it's nice to see the internet, which had initially been pegged as making the problem worse, actually making the problem better and encouraging a new market in ethically positive replicas sold more directly by local artisans not beholden to smuggling networks.