The government broke up the Ma Bell monopoly due to uncompetitive practices. Not until state regulation & later the 1996 Telecommunications Act, which was a regulation, not a deregulation, stipulating ILECs had to open up & allow CLECs on their networks did we see the flourishing(and eventual crash) you're talking about. The dot com bubble probably helped as anything Internet related was hot.
Do you really think the Baby Bells would have wanted to share their infrastructure with competitors? Judging by how they're trying to get back in bed with each other, my guess would be no.
It is a non sequitur argument to suggest that had telco's not been deregulated in the '80s, we would still have had CLECs building out the dialin and ISDN Internet of the '90s; that argument leaves out the fact that the RBOCs the CLECs piggybacked on were themselves the product of deregulation.
I am not sure you understand what "deregulation" is. Certainly an antitrust & monopoly busting lawsuit from the US government is not deregulation. When a regulated monopoly is broken up into smaller, regulated regional monopolies, that is not deregulation. It is also not deregulation when state & federal law has to mandate that line sharing be allowed.
Deregulation is the removal or simplification of government rules and regulations that constrain the operation of market forces.
The break-up of AT&T & the 1996 Telecommunications Act were nowhere near deregulations.
Also I certainly do not believe that AT&T would have broken itself up or the regional operators would have opened their lines up, had it not been for government regulatory actions.
Do you really think the Baby Bells would have wanted to share their infrastructure with competitors? Judging by how they're trying to get back in bed with each other, my guess would be no.