I don't really see anything slimy or unreasonable about any brokerage choosing to sell order flow. I personally would rather my brokerage sell the order flow and give me free trades, than guarantee I get scalped by giving me a $7 haircut on each side of my trades. I also see no reason to expect or assume that Robinhood, or any other broker for that matter, should not be making money off of their customers for the service they are providing. They are a business after all.
High frequency traders as a market participant also don't bother me. They help provide liquidity to the market, and make sure that when I want to buy/sell shares or options then I am able to do so. My last 4 trades in AMD yielded gains of 65%, 54%, 34%, and 28%. If they make a few pennies off me while I'm making tens of thousands of pennies then I guess I can definitively say I'm ok with that arrangement. And whatever pittance they make from front running my trades in Robinhood, I make back in dividends and capital gains from CSCO, MSFT, IBM, and all the other tech companies in VTSAX that profit from the millions of dollars that the HFT firms spend on infrastructure.
I was half expecting to see a disclosure of a long position in IBKR by the author, given that Interactive Brokers is apparently where the "sophisticated retail traders" hang out as opposed to the unrefined peasant masses that inhabit Robinhood.
I don't really see why the SEC should require more disclosure from Robinhood than it does from other brokers.
Prior to Robinhood showing up in 2015 I would have needed a about $2,000 to get started trading. When Robinhood came along I was able to get started in March of 2015 with a grand total of $140. And since their arrival they have done nothing but improve their platform. For me Robinhood lowered a barrier to entry into the market that to be honest should have been lowered a long time ago. I for one am welcoming the disruption Robinhood is providing to the brokerage services industry. And I will continue to enjoy utilizing their platform for my hobby trading.