Most of those networks also evolved gateways to interconnect to each other. The history of technology is often one that starts out with proprietary interfaces that evolve under user pressure to standardized, open interfaces. We see that playing out yet again in the iPhone vs Android competition.

As soon as there were two computers, people tried to connect them. The more they got connected, the more universal people wanted those connections to be. If commercial companies wouldn't do it, non-commercial entities would (after all, look at linux and the enormous success of free software). Heck, even I worked on hooking computers together back in the 70's using ad-hoc parts and wires and (never having heard of arpanet at the time) even sketched out how a decentralized "web" might work.

The idea that a decentralized fault tolerant network is such a novel concept that it required a government to think of it doesn't make a whole lot of sense. Even the telephone system is decentralized. There are decentralized fault tolerant systems all around us as examples.