Yeah, I'm trying to use more question marks and hedging "as I understand its" here. I've pentested huge clearing systems before. But I'm not going to lie and say I understood what the hell they were doing (also, the people at those firms made fun of clearing as the most boring conceivable stuff to look at).
But (1) lots of experts keep saying that Robinhood can't use customer cash as collateral to DTCC, and (2) DTCC's published rules seem to say that Robinhood owes collateral margin or not.
So like, I'm willing to bet that the margin stuff is a red herring, but I'm not willing to WSB-bet it.
A true insider would alternatively laugh or cringe at our crude analogies and simplifications of what's really happening inside the factory.