Why Bonding every metal chassis to the station's safety ground means that if a hot conductor inside the equipment contacts the case, the fault current has a low-impedance path back to the source, tripping the breaker or blowing the fuse instead of leaving the case energized. Without that bond, a chassis can float at line potential and shock anyone touching it, especially when they simultaneously touch another grounded item like a mic or a rack. The purpose is personal safety: the metal surfaces you touch stay at or near ground potential.
Watch out The choice about preventing a blown fuse is backwards, since a proper safety ground is exactly what lets the fuse or breaker open on an internal short. Grounding the neutral is the job of the service entrance panel, not of your radio's chassis, and RF overload is handled by filtering and attenuation, not by the green wire.
Green wire = people protection. Chassis ground keeps the metal you touch at zero volts.