The main value that an agent provides is listing your house on the MLS database, hosting open houses, and otherwise trying to attract customers to your property. As a seller, you're generally required, by contract, that any sale you make will pay out a commission. If you're not under any contract and a buyer shows up, then you're under no obligation to pay their agent. Of course, their agent may well steer the customer away from your house for precisely that reason.

Now, when you're dealing with BuyOwner or any of the other modern alternatives, it's unclear who exactly gets paid for what.