I tried Tech Crunch without adblocker and I would have to click out 16 "partners" after clicking "read more" two times. There is like hundreds of "IAB Partners" of which an unspecified amount need separate opt-out on their websites. It is not clear if "select all" opts out or in on the "IAB Partners".

So I guess exactly zero visitors opt out there in the intended way. So 100% "opt-in".

I tried to opt-out from all to see how many cookies would be set anyway but gave up after 5 minutes.