The key to understanding the purpose and function of grounding is to understand what the term "limit the voltage imposed" means as stated in Section 250.4(A)(1) of the NEC.
It is often stated that the goal is to establish a "zero" reference to earth on all non-current carrying metal parts of a premise wiring system. This causes great confusion. Many assume this means that during a surging event, the grounded, grounding, and metal parts of the system will remain at zero thus preventing shock or fire.
What is actually happening as the ground potential rise occurs during the surge event, all parts grounded to the earth will rise and fall together. Thus, a person in contact with the ground and a grounded part will have no current flow through them as no potential is created between those objects.
Without this bonding and connection to earth, the ground potential rise on parts of the system can and will occur at different rates thus potentially creating a difference in potential. Even the smallest difference will allow current to flow through a conductive body.
So don't think of it as excessive voltage. Think of it as imposed voltage. The voltage on the premise wiring system and metal parts may be thousands of volts as would be tested from a remote point. But like a bird on the wire, everything bonded togther creates a single rise and fall of the surging voltage, thus no voltage reading would be present between those bonded parts.
