Let’s say Firefox went full privacy absolutist, with all tracking and advertising networks blocked by default. That would probably be the best user experience initially, but websites wouldn’t make any money from visitors outside of subscriptions, direct donations, or (if they can sell them) direct advertising. It would probably just encourage more sites to stop supporting Firefox completely, which is already enough of a problem that Mozilla maintains a list of hacks to make sites work properly in Firefox. Mozilla removing all analytics from Firefox itself would also make fixing bugs and prioritizing development more difficult.

Idk my read is that every browser has to do this a little bit, or else websites will stop devoting resources to supporting that browser. Firefox’s solution seems pretty reasonable when you take that into consideration. And Firefox still isn’t trying to stop you from installing 20 privacy add-ons and nuking anything that even whiffs of an ad.