Why not both? They certainly are small players in a big machine, but the reality is that any engineer capable of getting a job in FAANG has plenty of other options that are less morally dubious. If they chose FAANG in spite of this they either don't believe it's immoral or are willing to look the other way for money/prestige.
I certainly wouldn't advocate for writing people off entirely based on their work history (after all, it could be that they went in not realizing the extent of the harm and that's why they're leaving), but I do think it's a factor worth considering.
Do people typically put that specific information on their resume? Alphabet employs over a hundred thousand people, 99% of them won't have looked at that at all. I personally don't work at a FAANG but I'd take the chance if I got it - the bucks are so monstrous compared to my current compensation it would be borderline unethical to not accept a position when I know how much it could help my family.