While there is a large public appetite for breaking up monopolies, it really does seem that antitrust policy has sadly become something of a bygone era.

A decent authority on the subject is Matt Stoller's book Goliath [1], which lays out the history of US monopolies and how they formed the bedrock for these modern tech companies. Their strategic dominance is no mistake. He argues that our era of monopoly power goes back to the resentment of New Deal reform, which began percolating in the economics department of University of Chicago in the 1960s and, in the 70s, entered public policy.

[1] https://www.amazon.com/Goliath-100-Year-Between-Monopoly-Dem...

Matt Stoller wrote a really interesting book giving a history of monopoly power in America: https://www.amazon.com/Goliath-Monopolies-Secretly-Took-Worl...

On my winter reading list :)