> * not too many super-rich / billionaires, who can just buy anything they want anytime, or ruin the careers of people going against them, hence people probably acted more freely.

The provided timespan encompasses the 'gilded age' era, which saw some ridiculous wealth accumulation. Like J.P. Morgan personally bailed out as the US Treasury at one point.

Much of antitrust law was implemented to prevent those sorts of robber baron business practices (explicitly targeting Rockefeller's Standard Oil), fairly successfully too. Until we more or less stopped enforcing them and now we're largely back where we started.