Oh . I will try again.
The boost controller pulses the solenoid to control how much air is being bled off. Not only would that slightly wear out the solenoid as it is being used it is pretty noisy.
So as to not wear the solenoid or make annoying noises ebc's will only start to pulse the solenoid when it sees 0 vacuum.
Therefore if it plumbed up to never read vacuum the solenoid will be pulsing all the time, wearing it out and annoying you with the noise.