Very true, you need absolutely no flight planning knowledge to drive a 737 / A320 up and down the east coast
the thing is, not all jobs are driving 737s up and down the east coast. You might find yourself rostered for Christmas/ Cocos island, working real life PNRs or with a U/S autopilot and nav system navigating a cyclone in the Gulf Of Carpentaria - both of which happened to me in normal airline service in Ansett.
Or or you may never see an airline, and end up in a GA company flying freight in a Westwind with zero company support, flight planning every night from scratch.