There is a rather large difference between how you do interfaces for people with training who are experts and the amateurs that Robinhood is targeting. It is the difference between a full cockpit and the interface you put on something like Garmin's autolanding system[1].
So, yeah, I'm blaming the interface people at Robinhood because they are targeting a non-broker segment of the population and need to find a way to put that information a broker would give you into the interface. This information includes things like "you do not own this much money" at a minimum. Facts are amazing things, but eventual truth might of save this person.
If you target a group of people, its your responsibility as a UI designer to make sure your interface is actually safe for that group of people.