While in theory that is true, Chromium is still mostly controlled by Google. Some people may decide that they are going to maintain forks of Chromium that strip out certain features of Chromium, but the pace of development is relentless, releasing new builds several times per day. It would take some seriously deep pockets to be able to staff developers who can keep up with the contributions from Google and Microsoft and others and ensure their fork remains up to date and not broken.

So yes, someone could change that open source code, but it’s really not feasible in the long run, and so Google (and to a lesser extent Microsoft), can control the browser experience for the majority of desktop users, including things like Manifest V3 or that “Digital DRM” that we were hearing about a while back.