I see it as nothing more than either gimmick to give users something the can get on their own (in case of FX being disconnect and control it themselves so if anything breaks, they can control the fix) or in case of google trying to implement something that allows them to take control over your choices. Why does a browser need to implement something that is already well implemented and is under user control and open source (while Chromium is open source, the crap known as Chrome is not, just like Dragon by Comodo isn't) so anytime they need to embed something in their code to remove control from the user and dictate behavior, I have an objection to.
Do you realize that this feature would give Google absolute control and knowledge to track everything you do, think about it, a blocker, be it ABP, uBlock or whatnot has to read EVERY URL, EVERY LINK, EVERY RESOURCE, to filter it, so now you can keep Google out by blocking their shit, you think if it was under their control, they would allow that? Plus, the very act of "intervening" on your behalf gives them access to things about your activity that you absolutely CANNOT do shit about to stop. Something to think about. Anytime something is part of the browser framework and out of user control, it leverages to the favor of the vendor. This is nothing more than them acknowledging they are losing to the adblocking crowd and trying to bring it in house so they can still get the data they are losing and continue their users = $$$ policy by circumventing the system to use an alternate way to the "cat and mouse" game of whack-a-mole with filters by just bypassing them at the core level.
Mozilla/5.0 (Windows NT 10.0; WOW64; rv:53.0) Gecko/20100101 Firefox/53.0