> They were killed by foundational technology shifts that were orthogonal to the industry.

That's the point. Markets aren't stagnant. When changes happen, monopolies are susceptible to being unseated.

This is very wrong because monopolies destroy the very competitive and innovative landscape that is necessary to unseat them, and in the process impose massive social harm in the form of higher prices, worse products or services, increased concentration of wealth, reduced employee compensation, political corruption.

America experienced uncheck monopolies during the Gilded Age. Most thought that rapid industrialization, economic growth, and technological advances would have resulted in enough competition to create an economic utopia. Instead, even while the United States experienced a surge in wealth and prosperity, the underlying reality of political corruption, social inequality, and labor unrest created a nasty, brutish existence that was only solved when the Trust Busting Roosevelt's transformed America by breaking up the monopolies.

If you like free market capitalism you can't be in favor of monopolies, and if you dont want monopolies you need STRONG enforcement of antitrust M&A regulation. We are well past a correction since Regan stopped antitrust enforcement. I would argue that all of our political chaos since the 1980's can be traced primarily back to that single decision.