"Off (No Color Adjustment) Turns off color management in your printer software so you can manage color using only your application software. Note: An ICC profile is required if color management is turned off."
Bu even if you turn it off, and use acpu the grayscale of profile is bad as it can be:
ColorThink shows light colors 2.2 to 1.3 at 50%.
A printer like EPSON L850 shows value of 0.5-0.1 at 50%.