Real helicopters do have flybars. The classic Bell-Hiller rotor system is the most notable. Undoubtedly, the most famous is the Bell UH-1 Huey. To control gyroscopic forces and asymmetric lift, the designer either uses a flybar or a rotor system with complex hinges and dampers.

Granted, many modern helicopters use a semi-rigid or fully rigid rotor system. However, such systems rquire large amounts of effort (Hydraulics) to move and complex blade and swash plate design to offset asymmetric lift via flapping and lead/lag of the blades.

The thumping you hear is not supersonic. It is a result of asymmetric lift. The blade is moving around the plane of rotation like a stripper seeing $10 bills waving in the crowd. Some designs 'almost' eliminate the whocka-whocka. The Hughes OH-6 (Loach) sounds more like an angry bumble bee than a helicopter.