By that logic google can not make any changes to their browser unless all forks agree to it, as the forks will definitely not be able to continue maintenance for long. By this logic it makes more and more sense to not open source anything and keep your product as tightly closed as possible (what Apple/MSFT have been doing).
It’s explicitly changes that are a net negative for users and privacy (e.g. manifest v3) or try to circumvent the web standards process (e.g. WebUSB) that are problematic and would be of interest to forks. Most changes are fine.
