Question about C/C plate install

Is this necessary even if you are replacing the factory struts with aftermarkets?

(quoted from MM install directions)
Step 1. Before dismantling anything on your car, lay a straight edge across the fenders and measure down to the top of the strut shaft. Record this dimension, you will need it later. (end quote)

Why you need it later:
Step 24. If the car is lowered from stock, position the spacers so that the top of the strut shaft is higher than the dimension recorded in step 1 by the same amount the car is lowered. Example: If the car is lowered 1.25" from stock, position the spacers so that the strut is 1.25" higher than the measurement recorded in step 1.