Except for rules put into place by Dodd-Frank make that a legal requirement for all brokers (to remove systemic risk from DTCC). You can argue that it doesn't m

Except for rules put into place by Dodd-Frank make that a legal requirement for all brokers (to remove systemic risk from DTCC). You can argue that it doesn't make sense for fully covered cash accounts - but it's not a decision Robinhood could make on their own - they are mandated by law to post that collateral from their own operating capital, and not use client assets (like the cash in their account).