They are trying. But it won't work.
I think if you really want to build something like that, you need real momentum. Perhaps the ladybird folks can succeed here, the future will tell. I don't think Mozilla has enough momentum left.
https://www.digitalapplied.com/blog/browser-market-share-202...
Firefox is between 2% and 3% now.
What do ad/tracker extensions do to that stat tracker?