Parler relied on several external services for security; but when those services were yanked away (due to Parler hosting neo-nazi and insurrectionist content), their code took the absence of such services as a reason to approve whatever action the user was trying to take. It’s the equivalent of your house security system letting everyone in if the phone-line goes down. There’s so much more to the Parler hack, from the lack of rate-limiting to the ability for people to pull down 60-70TBs of information from Parler’s AWS hosted storage, which — to add insult to injury, results in a massive egress bill from AWS to Parler, on top of AWS no longer hosting Parler.