The action in the 90's wasn't to break up their desktop dominance, it was to prevent them using that power to dominating the internet too.
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.