As a user of RobinHood I have not felt any specific push for buying single stocks. A lot of people just buy index funds on RobinHood. If RH had made it more difficult to buy those compared to single stocks, your claim might have some weight...
If all RobinHood users followed sound "buy diversified ETF and hold" investing advice, my understanding is that they'd go bankrupt.
If I had browser data from everyone on RobinHood, and was able to track which stocks they were looking at, I might be able to make money front-running.
If Robinhood is incentivizing or encouraging frequent trading by users, that's not really good in my opinion. It doesn't make them worse than other brokerages, but it doesn't make them better either. And with a name like Robinhood, they are positioning themselves as white knights.