There are other search engines and one can easily just type bing.com into their browser and set it as the default. Even on Chrome.

I'm not sure why you remember MS the way you do. There was a much much larger barrier for consumers to move to a different OS. If you owned a PC you pretty much had to run Windows. And MS made it extremely difficult to use a non-IE browser in the OS.

That doesn't mean I think they're innocent in all things but I don't see how their search market share is a monopoly target.