Ive outlined something at least 90% accurate to how this works in another post I just made.
We are talking about the keyboard itself intelligently adjusting its sensitivity thresholds for keys conditionally, and also intelligently cancelling keyboard input signals, all according to software/hardware on the keyboard itself.
Its happening at a lower level than the program receiving the inputs from the keyboard.
The differences are in 10s of ms, but this becomes a huge advantage of artificially granted, reduced reaction time in extremely fast paced twitchy games.
Also, a macro usually refers to a situation where a key is bound to give the input of multiple inputs simultaneously (jump+grenade), or, a set, timed recording of specific key presses, all initiated by pushing one specific key.
Sure, you could make a macro for strafe left then right then left then right for 3 seconds… but this keyboard tech makes it so you can have a faster reaction time and have the ability to do the equivalent of making up such a ‘dodge dance’ on the fly, customized to your exact situation at the time.
Chained command macros really only make sense in MMOs or fighting games, they don’t usually make much sense in FPSs.