If we think 20th century cohesion disappeared because of few policy tweaks, we'll be deluded into thinking we can get it back (minus the bad parts, somehow) with a few countertweaks. And then we'll waste our time trying to eliminate fragmentation, when we'd be better off thinking about how to mitigate its consequences.
This is one of his best essays. However, PG is making an assumption here that is incorrect:
Which in turn means the variation in the amount of wealth people can create has not only been increasing, but accelerating.
The assumption that he is making is that wealth is something that has to do with work. If anything, to date, wealth has little to do with work, and more to do with organization. For example, technology did not enable Mark Zuckerberg to do enormous amounts of work. It enabled him to organize communication and to create an efficient organization to execute it. Same with Uber. Same with Ford. Those performing work get little wealth, whereas those performing organization get a lot.
Decentralization of organization is going to upend this ecosystem. In time, the ability to drive a stranger across town for money will be a matter of leveraging a decentralized network. It will be a public resource, not administered by government, but simple there, like air. Furthermore, money is a poor proxy for value, and it does not have a reputation component. Reputation is going to become part of wealth.