US Big Co world dominance refers to the way Google, Facebook, Apple, and Amazon control search, social media, mobile phones, and eCommerce in the western world and thought that dominance US has financial dominance over most of the (western) society.
These Big Cos have a monopoly around their core business, which prevents real competition from emerging. You can see this very clearly in Europe. The biggest Europe-based Internet company is Spotify, with less than 300M users. Further, Google and Apple compete aggressively in the same field with Spotify and utilize their monopoly to gain a competitive advantage.
There are many people, like DHH, who believe that the US Government should break up the monopolies of Google, Facebook, Apple, and Amazon. I concur, but find it very unlikely that they will be broken up by the US Government. These digital giants are part of the US’s power. As long as the companies act in a way that is beneficial to the United State’s political goals, there is no good reason for the government to break up the companies and reduce their control in the digital space.