If it comes to scam I understand although it feels to me these blacklists go way further. I remember a list you once published and ruined many great writers with. Not because they were scamming, spamming, stealing keys but because they shouldn't join different social media.
You might find this childish to start about but I notice many behaviour on platforms/social media is childish, unnecessary and feels like dictatorship. Facebook, Twitter are great examples of it but they aren't the only ones.
If people are adult enough to join, write, can read the rules about keeping your key safe, use debit cards with punches (same message keep it private) are those rules necessary? Is all this bureaucracy necessary?