Keep in mind that both of those technologies took years. TCP started development in 1973. It didn't fully mature for another decade, and then it wasn't mainstream until 1994-1996.
And even then it was the web that drove the adoption of the internet, not the other way around. Until the web, the internet was more of an academic curiosity.
> Networks can benefit from economies of scale without the rent seeking bottlenecks of centralized agents.
But there are side effects of non-centralized agents -- everyone needs to agree upon running the same algorithm (forking, security holes, etc). And immature networks can suffer a majority attack.
Meanwhile from a security perspective, there's greater efficiency with a centralized system. One security hole can be fixed for everyone on the network in one spot.