It's the element of randomness as opposed to the applicant's accumen that makes me question it.
I've done FAANG interview processes and I have friends/colleagues who have done them before too. Often the people who get jobs with them apply every year (or as often as allowed) with roughly the same CV, and do roughly as well in the practical tests, but they can end up being weeded out at different stages of the process seemingly at random.
It depends on factors like the mood of the interviewer, or the standard of the other applicants, etc. The whole thing is just so hard to reach the final stage of that I am having difficulty imagining that there are many people who have been in the position of being in the final stages for more than one role.
Edit: I have an extremely talented colleague at the moment who used to work for Meta and he had to apply an insane amount of times despite the fact he is technically extremely proficient.
It's just my opinion, man ¯_(ツ)_/¯