Brokers will not show your house if listed only on zillow. And most offers come from clients with brokers. People with money don't shop for a house on their own. Buyers brokers will also not show homes that have too low a commission. They will flat out lie and say its off the market or under contract. Pay the extra and give a 6% commission with 3% to buyers broker and get more offers. MLS still rules when it comes to actual offers.