The text in the email literally says "Even when no action is taken based on feedback", so, anyone who's making the argument that they are going to write their hearts out is just kidding themselves. If you want to vent, write a diary (for old people) or just say 67 for the youngins.
Here's what boycotting it does. It's not mandatory, so, does anyone have a good argument for losing your job if you don't participate? Not participating diminishes their little game where they collect sentiment data and make staffing decisions based on it. I am doing my part, please consider doing yours.
Have a great rest of your life.