I can only argue back that the state of AT&T was such that it was such a massively profitable entity that exuded such power in terms of resources that what you are describing would not have been unique to AT&T had a less monopolistic situation arisen. The technologies that AT&T advanced, while notable, are far from impossible to have emerged had other entities had a fair share of the resources that AT&T monopolized.

To say AT&T should not have been broken-up due to its achievements is akin to say that Mussolini should have stayed in power because "he made the trains run on time". Yes, maybe, but at what other, hidden costs?