Why you can't easily make it to the top in a closed network without patrons
The publishing world is an interesting example.
Mainstream traditional publishing is very much a closed network, you have to go through the gatekeepers, stick to the script etc.
But the explosion of indie and self publishing has created a parallel open network which allows much more open access, innovation etc.
It's particularly interesting because a lot of authors end up building a hybrid model of both in order to reap some of the rewards of each.
When I worked in San Diegos equivalent of Silicon Valley (Sorrento Valley) 4 decades, once you worked in a mid sized communications (Radio Frequency) company you were in. Nearly every company this category descended from a company called Ma-Com Linkabit. Engineers from that company spawned 17 companies. Qualcomm was 2nd generation company in that chain. Once you had a few years at any one of those companies, there was an overwhelming chance someone who knew you worked at a company you might apply at. If not know you they knew someone who knew you. It made moving and advancing rather easy as long as you were at least reliable as a worker.
It also seems like closed networks are more susceptible to corruption. Both Chicago and Southern Italy which you mention here are famously corrupt, but I can think of other examples. Perhaps when who you know becomes the most important factor in your success, then favors emerge as currency.
A couple of thoughts:
1. You could add Allentown, PA (open networks) and Youngstown, OH (closed networks) to the list of example cities. There's a great study comparing the two at https://web.mit.edu/lis/papers/LIS04-003.pdf .
2. Having lived in Northern Virginia for 12 years, I've observed the DC region's open networks on many occasions, and can say that it's led to a much more dynamic culture than conservatives tend to assume. (That the dynamism is sometimes oriented in a way that's counter to the flourishing of the rest of America is certainly a problem, but not in a way that fits the "big government is bad and lazy" narrative.)
Also, Carter's right that the cost-of-living is high but mistaken about the taxes: Virginia and Maryland, where the vast majority of metro DC residents live and where Amazon HQ2 is located, aren't terribly burdensome either in income tax rate (the top bracket is 5.75% in both states) or in difficulty of compliance.
When I was in graduate school and needed to travel to the UK to research my dissertation, I had to get letters of introduction from my committee chair, who was a fellow of the Royal Historical Society and had many other affiliations, in order to gain entry to several archives. Definitely a closed network!