This is just a random person's opinion on the topic, but it's always good to hear different opinions from your own. I decided to read through the article and basically the guy concluded that Robinhood will likely the the BEST place to buy crypto from in the near future. His article just touched on some points for why it could hurt rookie traders that just use market orders and he questioned if they would be able to handle the influx of new users for crypto. He did fail to mention that it is only rolling out in 5 states to begin with so there wont be nearly as high of a number of signups as it says on the waitlist page until it is rolled out to more states in the US.
It seems our conclusions are quite different. There is lot of information but maybe not explained very well.
For one, Robinhood's apparent use of the word "market order" is confusing even for a non-rookie. I personally have never seen people saying market orders but actually it was a limit order. What are other exchanges/markets which does this?
Second, Robinhood not having it's own exchange market is worrying because they have to rely on latency between their platform and the connecting exchanges. So only limit orders which are far out/in the money will work well. If the market is moving too fast this is a recipe for disaster.
On the same topic, if the exchanges are down, something which happens quite frequently, Robinhood is going to be out of commission too. So the reliability is also questionable.