https://en.wikipedia.org/wiki/United_States_v._Microsoft_Cor...
Microsoft not being broken up wasn't about them not being guilty. It was about prosecution (under the new GWB administration) seeking a lesser penalty.
"Although the D.C. Circuit found that it was possible to examine high-tech industries with traditional antitrust analysis, the court announced a new and permissive liability rule that repudiated the Supreme Court’s dominant rule of per se illegality for tie-ins, due to the court’s concern for the dynamic effects that a per se rule would have on innovation."
Ergo, the tie-ins were found to have happened by point of fact but not found to be illegal by re-interpretation by the courts of the illegality of tie-ins. The Justice Department then reached a settlement (the win on their side being that they wouldn't have wasted the years of prosecution).
This goes a way towards explaining why there hasn't been a similar Microsoft-scale antitrust case since the Microsoft case in the US.