On a helicopter, you also reduce the induced flow coming in from above the disk (it bounces back from the ground)
Oh, Paco, Nick Lappos will be so sad that you said that.
Same as an aeroplane wing, the rotor has a reduction in induced flow with the airflow changing direction because of the proximity of the ground. It doesn't bounce back, it doesn't increase the pressure under the disc, there technically is no "pressure bubble", just a reduction in induced flow. So for the same collective position, you get more lovely lift.
Sassy, sounds like you speak from experience, but being at 5800 N2 with the horn bleating away (I suppose you could cancel it?) would scare me a bit... I recall a flight with BO'L where the RPM light was on, and he took out his black chinagraph pencil and coloured it in.