Schwab has a note that they're limiting volumme on specific stocks today. I agree with the point that any of the major brokers would have done the same, but I think that's more an indictment of all of these organizations than a defense of RH.
I'm just not sure about that until I see the volume and see that as a reason for them to not let me buy a security. They can have their systems go down... I mean obviously that's not ideal but that's something that could happen due to volume - but Robinhood didn't go down. Vanguard didn't go down. I can still buy via Vanguard right this second - what does the volume have to do with it?