Yeah, I think the root comment of this thread is talking out of his ass. Third-party trackers are not needed, and wouldn't make sense to use, to discern browser market share; browsers self-report their identity and operating system unless specifically configured not to. For example, my User-Agent string in my GET request to retrieve Hacker News is: "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:120.0) Gecko/20100101 Firefox/120.0".

Except we should be pushing for the elimination of user agent strings, too. They just end up being used as a lazy way for lazy developers to not test for capabilities.

The most recent example I've run into is Snapchat's web client: It reject's Firefox purely by user agent string, but then works perfectly in Firefox if you just have your browser lie.

I strongly agree. I don't think a website is going to do anything with my user agent string that benefits me. I'd much prefer a web where websites can't do things outside of the standard. We ne er needed webmidi, but a company that makes a browser/is hybrid definitely wanted it.

Speaking of Google, won't this interfere with their "look we're not a monopoly" payments to Mozilla Corp?

That's the sort of this that should be illegal for anticompetitive reasons.