We intentionally fail the purple phase to clean up the adds from previous phase since Purple only spawn 1x Rectifier + recognizer adds. This make things more tidy than rushing through purple, at least for us.
This is what my guild does as well. It just makes it easier on everyone to burn 1 core during the purple phase and leave the other one at about 20%. Fail the phase and deal with the rectifier then burn the last core easily. This sets up the last phase really nicely for us.