OK so I am not an expert here at all, but my broad contention is that much of the modern way business works traces back to:
https://en.wikipedia.org/wiki/1975_Stock_Brokerage_Commissio...
The equivalent in the UK — the Big Bang — was very much fresh in the minds of my leftie economics teachers in 1990 :-)
https://en.wikipedia.org/wiki/Big_Bang_(financial_markets)
On top of the creation of NASDAQ and subsequent NYSE reforms that opened up electronic trading and allowed banks to start selling stocks, these things meant that ordinary people, individuals, etc., developed more of an interest in the stock market and of "business" as an abstract.
This did two things: first it means that there's so much more heat around IPOs and so much more interest in them. But there's also an amateur/individual obsession with quarterly performance over the slower, institutionalised trading that went before it.
That changes the culture of business, Wall Street and London so much that it fuels the market for business schools, MBAs, economics degrees.
Then once you have the broker-driven (and exchange-competition-driven) obsession with the hunt for IPOs, you start to see the modern venture capital market, and thirty years later after a few crashes, the reactive rebirth of private equity.
But before these reforms, people on the streets in either country did not really have access to the stock market, and stock trading was sort of a gentlemen's club: they were absolutely furious that the fixed commission era was ending.
Fixed commission regulated by the SEC is such an alien concept now.
The startups I worked for in the late 1990s in the UK simply could not ever have happened before the Big Bang. The entire culture of venture capital changed.