As long as MITM proxies still work (which is something that Enterprise customers demand --- even the notoriously-closed Chrome needs to), it will always be possible to filter pages outside of any browser. I've been using one for over 2 decades and it works in any browser.
However, I am also concerned that this is an "embrace extend extinguish" move.
What would prevent sites from just injecting ads into their content server-side? You'll always need both element and request blocking.
Tell me more, what's your setup.
I use uBlock Origin in Firefox and network ad blocker. Wondering what other options are there.