I remember learning to fly helicopters in Jet Ranger (206). There were cautions against using the T/R and collective to slow down the rotor when we shut down after a sortie at Whiting Field. (Can't recall if it was in the NATOPS or the squadron SOP, been nearly thirty years).
Of course, my instructor nearly always, when he was doing the shut down, added a bit of rudder and a bit of a colective ... but woe unto the student who did that.
FH1100: agree with most of your post.