Does this really surprise *ANYONE*? The companies didn't create the algorithms for criminal predators, they created them for marketing lists, and of course, once the money started rolling in from toymakers, etc., they sold the lists to any account that paid. Pretty much all social media companies do this; it's the bulk of how they make their money.
I'm not saying it isn't morally reprehensible to make money off kids without caring who might get hurt; of course it is, and there was certainly *potential* for harm there, but in my own kids' case and those of probably the vast majority of others, the predators paid for lists that didn't help really them, just because FB lost cachet with kids within a very short time after it was opened to non-college-students, and the baddies were wasting a lot of time and energy targeting abandoned accounts. I remember that my DS (now 26) was required to create a FB account in high school for a job-networking assignment; I know for a fact he removed all the personal profile info the day after it was graded, and shut the entire account down the day he graduated from HS; he just didn't want to be bothered with the whole deal. My DD has a FB account, but it lacks all personal info and is fully locked-down, and she never posts anything or reads any direct messages: the only reason she has it is to follow her coaches and her sports federation.
I'm active on several private FB groups that are specific to hobbies that I have, not truely social at all; we all post nothing but tips and techniques related to the hobby. Once or twice someone has managed to hack into the group and post porn, but they are tossed out very quickly, and if the problem persists, the group will shut down and re-form under another name.
The only approaches my kids have gotten with recognizable child predation grooming tactics have come from online gaming sites, which are the richest hunting ground of all. I lost count of all the times my son was approached by people on gaming sites who wanted to make friends and give him massive amounts of expensive game credits supposedly out of the goodness of their hearts. I found out later that by the time he was 15 he had developed a technique to use them even more effectively than they sought to use him; he turned the tables using fake personas and extorted within-the-game money out of the less-clever ones while giving them absolutely nothing in return.