Ben put it well:

GFCIs are to protect people from electrocution. They do NOT protect the circuit from too much current. The slightest imbalance between the hot and neutral should trip them.

Breakers and fuses protect the circuit from too much current so the wires don't heat up and start a fire.

Too many workman pull out the third prong on plugs. This is, frankly, insane, especially when they work outdoors. My father did that constantly and to this day I'm amazed he died of lung cancer and not electrocution! I pulled apart his bench lathe as we were selling the house for my mom and in the switch box...he had bypassed the ground yet again! (the lathe is powered by a Jacuzzi pump motor--with Dad cutting out the ground). The switch went into the trash! When the lathe is set up again, it will be wired correctly.

Most towns and cities don't allow "Conduit grounding" or, more properly, a "mechanical ground" requiring, instead, an electrical ground.

For bonding, my town requires the ground to be insulated and green-jacketed. Also it's something like #8 wire--very, very heavy and everything metal is connected to it.