I’d argue it’s not bad at all. It very cleanly aligns incentives in a way that benefits both sides.

Another way to look at it is that there’s an “implied commission”, paid in the form of a perhaps slightly inflated purchase price, that largely doesn’t affect retail investors. And this all works out for quant firms because they make money off this at volume, at near zero marginal cost.

In fact, it’s odd that commission free trading didn’t happen a lot sooner. Etrade, Schwab, etc were rent seekers.