Fisho’s who use berleyBerley (“chum” in the USA) catch more fish. It’s that simple.
On a boat, the pier or on a beach berley cages are one method to entice fish into the area near you.
As the container you use has to be up for the rough and tumble of fishing a metal wire cage is durable and easy to use. With enough weight to get your berley down towards the bottom, maximising dispersion.