The breakup of AT&T killed the most productive industrial research center of all time: Bell Labs.
South Korea seems to be totally fine with Samsung running the majority of the economy, monopolies — when controlled through regulation — are not always a net negative for society.
I have enjoyed the benefits of information theory, fiber optics, lasers, UNIX, the transistor, and many other things which came out at Bell Labs.
Industrial research which operates on the 5-10 year needs stable recurring revenue and reassurances that the company will still be around to reap the benefits of said research. Monopolies provide the environment for this research to take place. I think the proper way to mitigate the harm done to the consumer by the monopoly is to closely regulate the monopoly. For example, the fee structure for AT&T’s long distance rates was regulated to not exceed certain levels which were deemed to be acceptable. Customers payed a reasonable price for long distance rates, AT&T had a stable income, and there was no threat of their business being upended so they were willing to take on long term research to improve their margins on the fixed long distance prices.
Yes, consumers could have been paying less for long distance rates, but where would society be today without Bell Labs? I think the harm AT&T inflicted upon their customers is heavily outweighed by the engineering and scientific progress they achieved.
South Korea seems to be totally fine with Samsung running the majority of the economy, monopolies — when controlled through regulation — are not always a net negative for society.