I read that article its very clear. Any idea as to why the "installed grounded conductor shall not be connected to the equipment grounding conductor or the grounding electrode." I am curious why this connection is no longer permitted?
For same reasons we separate grounded and equipment grounding conductors for circuits in same building - NEC just allowed us to treat the supply to separate buildings kind of like service equipment for a long time - with no real good reason, that finally changed with 2008 NEC.
The reason is when you have current in a conductor you have voltage drop. Take a conductor that is connected to a grounded supply and apply enough current to it to cause 3 volts drop over the length of the conductor. At the source end the voltage from that conductor to ground is zero volts, but at the other end it is 3 volts. This doesn't bother users of equipment if it is only connected to current carrying grounded conductors, the white wire of the circuit that never connects to metal frames of equipment. But if you should happen to connect that white wire with 3 volts to ground to the EGC, metal frames, etc. you now have all this exposed metal that carries some shock potential for users if they touch any part of that EGC system and true earth at same time.
Three volts may not sound like enough to be a problem - and often it isn't, but put yourself in a situation where things are wet or damp and that 3 volts can be lethal, and a GFCI won't help as it monitors leakage from the associated circuit conductors, not stray voltages on the EGC.