That's an interesting way to trade cryptos
I think this will make it easier to use for a lot of people rather than using a trading platform which may seem hard to use to the rookie user.
It would be if Ameritrade was actually allowing to trade them. There's nothing in this article about cryptocurrencies. This is a brokerage firm which mainly allows to trade securities. The only crypto-related thing that can be traded there from what I saw is bitcoin futures contracts, which is a speculated version of trading btc. Oh, and according to official info in 2017, to trade bitcoin futures there you need a balance of 25 thousand dollars. And it's not even about forming these contracts yourself like on cboe. It's about trading them, I guess, which is another step away from bitcoin itself.