A company owning a web browser isn't the problem. A company owning a web browser, OS and search engine shouldn't be a problem either. I don't know why the remedy can't actually address the problem, and the DOJ can't move more quickly to address antitrust across the industry. This feels like randomly cutting a baby in half, while the rest of the thieves, even those in the same family, are not deterred.
It is when Google compromises the privacy/security of Chrome because of their Ads/OS business.
For example, allowing first party cookies to be a maximum of 400 days versus Safari and Firefox where it is 7 days. These cookies are required by ads retargeting which is critical to effective ecommerce campaigns.
It also supports browser fingerprinting by advertisers which means that every random API Chrome adds (and they add a lot) directly improves their Ads revenue.