That's absolutely right, but it's not the point.
What matters is how much investment is required to offer an alternative to Google's Chrome. Does it take billions or does it take mere millions?
Building on top of Chromium means that it takes mere millions. And that changes the situation.
For that to be true, it is not necessary to wrest power from Google when it comes to deciding what does or does not go into Chromium as Google doesn't get to decide what goes into any forks.
Does any of this negate the power that Google currently has over web standards by way of Chrome's overwhelming market share? Certainly not.
What it changes is Google's margin of safety when it comes to imposing truly user hostile technology on everybody or stop investing in the technology.
And I don't mean "user hostile" in the sense that it enrages the HN crowd. I mean user hostile in the sense that many normal users will actually look for better alternatives on their own accord, not for political/advocacy reasons.
The fact that open source Chromium exist makes Google's dominance over the web far less assured than it would otherwise be.
> Building on top of Chromium means that it takes mere millions. And that changes the situation.
This simply does not follow. If you're building on the back of Blink you're still chasing whatever Google unilaterally decides to include in Blink. You need to do extra work to merge stuff you want and keep stuff you don't want properly disabled. Google has no impetus to make it easy or even possible for third parties to disable features in Blink. The cost to maintain a defanged Blink can very easily go from "mere" millions to billions if Google makes it difficult to merge upstream changes in defanged forks.
If web developers readily adopt whatever Google throws out, and lets be honest it's adtech companies adopting "features" to better fingerprint users without cookies, then a Blink-based alternative to Chrome will get zero uptake. If the top sites on the Web require Google's version of Blink/Chrome with all of Google's handy dandy anti-privacy features then it does not matter in the slightest that a non-Google Blink browser can exist.
You're pretending that Blink being Open Source is somehow going to affect the decisions of web developers (adtech companies). They are going to chase Google's version of Blink/Chrome because that's how they make the most money. Right this second Apple and Mozilla are just barely keeping Chrome from fully dominating the web.
Google is never going to make Chrome overtly user hostile. They're just going to continue to making Chrome an advertiser's dream browser because they are an advertiser. While WebEyeTracking might have some non-advertising use 99% of the user cases will be to make sure people looked at an advertisement long enough. If Google controls the specifications that define the web and sites adopt those technologies, there's no room for alternatives that aren't Google's Blink. Not only can defanged Blink not be practical but neither are non-Blink browser engines.