Algorand’s solution as originally stated is predicated on a non-colluding majority. At IACR when this algorithm was proposed, Silvio famously said as a counterpoint to the very apt criticisms that a colluding majority could defraud the protocol “my proof is that society exists!”

In the end I believe Algorand changed their algorithms to a more centralized approach for the sake of performance as fully distributed validation did not perform adequately. Please correct me if I’m wrong.