Well, by definition it's true for all trades that would occur without your help. In those cases, you're taking a couple cents and making it more expensive for a

Well, by definition it's true for all trades that would occur without your help. In those cases, you're taking a couple cents and making it more expensive for at least one of the other participants. That would cover, say, any institutional investor who is moving into a position. In terms of you justifying HFT activity, of course not. There have always been advantaged participants and HFT traders are simply those today. But the article was trying to justify HFT as manna for all participants, which seems unlikely considering how much money the industry is extracting for their liquidity-providing services.