All of those points are true, but you aren't getting that precise feedback from the game, you are getting that feedback from your computer. And seeing the mouse doesn't even give you precise feedback about the game. Sure you know exactly what you are inputting, but you don't know what that's doing. You don't know that moving your mouse is moving an in-game character around at a 1:1 ratio. You don't know if clicking is doing something in that particular part of the screen. Sure you can infer that info from what the pixel is doing and what the manual told you about the game, but the player inferring what's going on from their limited knowledge is exactly what this jam is all about.

I think you are confusing feedback as a whole and feedback from the game. The feeling of a key being pressed down is a form of feedback telling the player they pressed a key. Seeing the mouse cursor move around the screen is a form of feedback telling the player where they are moving the mouse. Seeing the one pixel turn on or off is a form of feedback telling the player what is happening in the game. The first is feedback from your real life keyboard, the second is feedback from your computer's operating system, the third is feedback from the game. If you start disallowing forms of feedback that aren't from the game then where do you draw the line? What if my game uses the current size of the game window as input, requiring them to resize the window to beat it. Do I need to somehow make them not able to see the window's current size?