Especially true if you are holding evidence that you knew it caused medical problems, but ignored that evidence and continued doing stuff that made it worse because it makes more money. At that point you pretty much have to start bribing people to look away, like the cigarette industry is notorious for.

Facebook has practically zero incentive to research damages they might be causing. Sure, they could do the ethically responsible thing and try to discover and mitigate issues... but if they were doing that, we wouldn't be at this state, would we?