If you don't know what the suction peak is, you won't understand the concept of centre of pressure, and if you don't understand CP you won't understand the stalling characteristics of a swept wing airliner.
There is no mention of suction peak in my PoF manual, so I obviously didn't need to know what it was in order to understand CP, or to pass the PoF exam for that matter. You can come down off your high horse now.