They created a ton. Transistors, solar cells, lasers, satellites, cell phones, LEDs, UNIX and C all came out of that monopoly. That's an unparalleled track record of technical innovation.
With a great deal of government subsidies and grants. Left to own devices, private companies don't do theoretical, long-tail R&D, and you can see this in the fate of Bell Labs under the tutelage of Alcatel-Lucent. Its staff was cut 90% and their projects were subordinated to narrow, short-term commercial objectives with a 3-5 year go-to-market horizon.
Such an environment does not churn out transistors, fibre optics and TCP/IP.
Such an environment does not churn out transistors, fibre optics and TCP/IP.