Yes its nothing we can prove without special cameras and technical knowledge.
I first tried hpet long time ago, having no idea what it will improve and noticed huge response difference right when I booted to desktop. Same thing with C1E and Speedtep when I bought new supposedly faster but very delayed pc. Before I seen all this "placebo no technical explanation/high speed cam proven" fixes by r0ach.
Some things have have no or imperceivable effect and they do no input lag reduction. I cant force myself into a placebo effect or feel more responsive input with 125hz + raw input like someone said it does.
Majority of gamers play with very high and always different sensitivity(most cant even turn 180 degrees with one swift motion), play poor console ports without 1:1 movement, games with major input lag problems and find nothing strange about it, and think "that its how it supposed to be". Some may even take and believe in insulting "weighted weapon movement".
Same thing when source engine server has constant drops to 5-10fps (or stupid 30000 rate servers with constant choke for everyone), 95% of people just say they have "no lag must be ur pc/connection lol", even thought there is a thing that shows servers fps. Or not noticing extremely desynced melee animation in some source engine games.
Or lcd vs crt war: people denying and defending with "no lag for me", "human reaction is 200ms" bs to the bitter end.
And they also are clueless to much things, same thing was for me when I first started gaming years ago. I just didnt know what was happening and how things supposed to run and respond, but I didnt have good internet connection to write "placebo" on forums.