The issues are extremely clear - and we don't have to prove Microsoft has abused a monopoly, that was shown in court, upheld unanamously by the Court of Appeals en banc, and refused review by the Supreme Court.
The current administration, in typical Republican worship of the extremely wealthy, allowed Microsoft to write it's own punishment. Interestingly they have not met the terms of the punishment they themselves wrote and the judge in charge has been getting a bit antsy.