Vacuum is what closes the diaphragms - once closed then it will pull more air from the filter. Because the valvetronics control engine speed (intake air to cylinder) - throttle body fully open - there is a fine line to accomplish vacuum within the intake and (un)restricted air thru the filter(s).

But all this is reliant on a closed crankcase system (no seal leaks).
And you'll always have blowby that may effect diaphragm operation.