The interest of the actual sky without an artificial horizon is to refer to the sky pointer connected to the emphasised large natural horizon, and ability to teach a safe scan.
As instructor of newbees I watched that the best students had an already educated sight and body tonic posture : practising gymnastic, deltaplane and theater ! That physical knowledge of level and vertical is the clue to learn to move in 3D . But we know that doing an exercise has much more efficiency than having the demonstration by the the instructor, and doing it solo needs a total confidence in what you are doing. It is the next step after demonstration. Only then you stop hiding the artificial horizon -if one- or may start simulator training for instrument flight first with the artificial horizon -so small!- and later with partial panel (is it how you call our french "panneau partiel"? ) with the final exercise described by Machinbird in the Cougar back seat with the "sadist" managing the unusual position and being so happy when his student does that well! We cannot jump over these steps. Not everything has been bad in the new method to teach piloting but any pedagogy mistakes have been made forgetting the third dimension and body adequate education.