I have a different recollection of the Microsoft case. The litigation was not about pricing and rebates, but rather bundling. Specifically it was the bundling of Internet Explorer as a freebie to drive out Netscape, and the persistent refusal to unbundle Explorer or disable it.
If Microsoft agreed to limit its discounting schedule, it does a fat lot of good for the competitive landscape, since there is no significant alternative for the consumer ! Nice agreement ! It allowed Microsoft to increase its profits and allowed the Bush DOJ to trumpet a victory ! A more effective remedy would have been to force Microsoft to release the source code of Windows, or breaking apart the OS and Office Groups.