They did make it costly for OEMs to install competing browsers: https://www.justice.gov/atr/file/704881/download

Abusing their market position (only viable desktop OS) to promote IE and attempt to get a stranglehold on the web is a significant part of what got them in trouble.

Excellent book covers the situation in more detail: https://www.amazon.com/Breaking-Windows-Fumbled-Future-Micro...