There’s a very specific legal definition of what a margin account is.
Robinhood accounts are Regulation T (aka Reg T) margin accounts by default. They have limits, yes, but they are very much margin accounts. That’s how they make their UX work.
The point is that typical user activity will be performed on margin, transparently. The flurry of synchronized activity caused a larger than normal draw on their margin, which further strained their working capital.
Yes, there is a specific legal definition (I did elude to that in the post you replied to).
Most people don't understand that definition and when they hear "Margin account" they assume people are making leveraged transactions which is not the case. Even Robinhood's FAQ and documentation uses the more commonly understood definition of margin. One of the primary "Features" of Robinhood gold is "Access to investing on margin". https://robinhood.com/us/en/support/articles/gold-overview/
This is getting a bit pedantic. The reason people are specifying that RH accounts are margin accounts by default is because it’s relevant to the financial situation. Functionally, they are margin accounts even if the end user isn’t entirely aware of it.
Robinhood accounts are Regulation T (aka Reg T) margin accounts by default. They have limits, yes, but they are very much margin accounts. That’s how they make their UX work.
The point is that typical user activity will be performed on margin, transparently. The flurry of synchronized activity caused a larger than normal draw on their margin, which further strained their working capital.