Is that a problem, however? Or more precisely, one that Mozilla wants to think is a problem and "solve"?
I use adblocking and such myself, but I think it should really be a personal choice --- browsers should just stay neutral. I have a suspicion that browser organisations taking sides in this will only lead to even more invasive tracking in the future, since this is a cat-and-mouse game. (Imagine if Firefox had adblock by default. It would just force adtech companies to come up with even more unblockable methods, since the defaults have changed.)