Because Google has an abusive search monopoly that harms consumers by providing a shitty experience and there are very few alternatives.There are a number of alternative search engines (Bing, Duck Duck Go, etc). These tend to have the same crap (to me) approach. But they're drive by the same exigencies - to help deliver advertising, to foil the most garbagy SEO and monetize the rest, to provide "answers" rather than just key-word search (IE, dumb things down for the masses).
Google has a browser monopoly and it has been integral to providing a moat for their search monopoly
I'm writing on Firefox, I love firefox and I've heard good things about Edge. Of course, Firefox is supported by Google and uses Google by default but I spent a year on Duck Duck Go and unlike Firefox, it really does suck. To expand, it's suckiness isn't lack of money but because it's clearly trying to do everything, all the bad things interface-wise, that Google does ("answers", weight-to-new-and-recent result, etc) but worse.
Edit: It's really terrible that all interfaces have become interfaces for morons, that the paradigm for any company is "we give you few choices and use sophisticated AI to give you the choice we think you'd want 'cause giving you choices and tools means you might not decide what we want you to decide". But this paradigm doesn't actually relate to companies being monopolies. It really is what some portion of people want/need and it serves any company that doesn't have organized nerds as their customer base. I'd love to get past this but "break up Google" doesn't address this.