I used to think monopolies were inherently progress limiting, but as you point out it's a mixed bag. Bell labs was an amazing center of innovation even as AT&T stifled the telephone market. Not sure corporate labs could exist today with the self-defeating (and legally incorrect notion) that the primary duty of a public company is to make money for shareholders. That philosophy today would/will prevent large companies from investing in their own future via plush corporate labs. There's a great quote from Alan Kay that Xerox did actually make enormous profits from their Xerox Park labs, as the labs invented laser printing, but Xerox decided not to make trillions by pursuing their invention of graphical personal computers and ethernet.