We kind of need ublock origin on the operating system level - even more so as the new laws mandate age sniffing of everyone, tied to usage and access to the www (see the concomitant fight against VPN; that is the long road here, the "but but but the children!" is the lie, the cake, the carrot on the stick).
Ultimately one could ask "but the do not track thing is harmless" - the issue still is that I don't agree that my browser should betray me. Naturally since Google controls most browsers, can we trust Google? But, even aside from Google, can we trust other browsers? We need more diversity here again, but also more quality on every level. I consider the do_not_track as actually a you_will_be_marked and thus tracked.