[001sky]

But it's a special kind of nefarious behaviour that really only affects other market participants who can react quickly enough to the information - i.e. it's mostly HFTs taking money from other HFTs.

This kind of behaviour that undermines the integrity of markets should not get a pass based on who it does or does not hurt, tho. If nothing else its bad PR that keeps people out of the markets or creates other "absences" or dark patterns from people not showing up to trade, fro whatever reason.