You are making exactly the mistake I am pointing out in my comment. Outside of the HN bubble nobody cares at all about a "thriving browser ecosystem." They want a browser that works so well they don't have to think about it and Chrome has provided that. And this is where Google's dominance has a tangible benefit. The amount of resources that Google can apply to Chrome development is massive compared to what could be done in the highly competitive market that existed before it.

You can argue that maybe a highly competitive browser market would lead to more innovation, but I'm not sure that's the case. Could a highly fragmented market build something that is as good as Chrome? IDK, but my (moderate confidence) bet is no. Browsers are a pretty mature product at this point and I don't think that competition would produce enough competitive pressure to outweigh the massive resources of a dominant near monopoly.