Just to throw it out there (I don't have the answers here), but "We made a private dark pool, tiny relative to the size of the overall market, and it was illiqu

Just to throw it out there (I don't have the answers here), but "We made a private dark pool, tiny relative to the size of the overall market, and it was illiquid without HFT" isn't really the same thing as "the stock market would be illiquid without HFT".