I find myself disagreeing with you. You are right about this being driven by interaction, and humans needing to see that something is happening. But even if you

I find myself disagreeing with you. You are right about this being driven by interaction, and humans needing to see that something is happening. But even if your application responds with "processing request", you have - at best - reset the timer. If it takes longer than one second from the reset for the data to be shown, the user is again entering the "is this slow or broken?" time band. The Nielsen thresholds appear to be fundamental to human nature, and I would be surprised if we have somehow managed to teach humanity to be less impatient over the past few decades. If anything, the dopamine-hit fueled online systems have taught the users to expect even more immediate feedback.