The government caused the phone monopoly and the slap on the risk had nothing to do with Microsoft's missteps when it came to the internet and later mobile. Microsoft still has the same dominance on the desktop that they had during the 90's.
Even before the government sanctioned their monopoly, AT&T was becoming a monopoly using strategies that the feds were arguing were anti-competitive and in violation of antitrust laws. You could argue the government first acquiesced their monopoly with the Kingsbury Commitment in 1913.
In the '20s and '30s, the government allowed them to resume buying up local carriers and established the FCC to set rates, but there was still tension and antitrust suits up until the '50s.
Like any relation, the government's and Ma Bell's was always "complicated".
they were pursuing a number of antitrust cases against them. Needless to say, AT&T's relationship with the federal government and regulators wasn't static over the next 60-70 years. Sometimes it was at odds, sometimes it was symbiotic.
What had more effect on IE being toppled by Chrome, the government or the most popular website advertising it on their front page and bundling it with third party downloads?
It was the control over individual customers that mattered not any particular market. The ‘94 act would have been quite prescient to be defending open internet access when first drafted in the early eighties.