There are two issues to your comment:

1. Trading (including risk management) is really complicated. It isn't something that you can pick up in 30 seconds after downloading an app. This exact scenario (where broker stops taking orders on a stock likely due to internal risk limits) is a great example of an unusual scenario that has to be risk managed. This isn't some nose-upturned view but a fact.

2. Many of the comments here are made in good faith but it is pure speculation. 500K reviews were apparently posted and automatically removed. In any usual day we'd assume this was the usual spam. Again there's speculation about why there were removed. My point here is that there needs to be time to actually find out what happened.