Chrome has a massive market share and Google abuses that market share by breaking web standards, and pushing people towards Chrome because "the competition doesn't work".

They act in bad faith and abuse their position to more deeply entrench their position in anticompetitive monopolistic ways.

That's the Crux of it.

Essentially, everything is Chrome, Firefox or Safari.

Brave, Edge etc are chrome.

Most people are using chrome.

Google controlling chrome controls what the vast majority of people use to see the internet, and then they change chrome to make it harder for you to block ads that they want to show.

There's no reason for chrome to break ad blockers unless it's owned by an ad company.

Edit: Google done some other shady things by owning it in the past as well.

Breaking up monopolies is a good thing, and Google arguably holds too much power. Chromium is being used in 70% of browsers, and the decision how to implement and develop web standards are all in the hand of one for profit company, which had little interest in keeping things open and accessible (and private).

A quote from this Register article sums it up nicely:

What we are forced to assume in turn is that Chrome is built by the professional developers working for an ad agency with the primary goal of building a web browser that serves the needs of other professional developers working for the ad agency's prospective clients.