Regarding it being a valid argument, I would say that for functional strength front squats and overhead presses are much better than back squats and bench press.
bingo the only functional lift in powerlifting is deads. If you want functional strength then strongman training is where it's at, not powerlifting. Picking up sand bags and kegs, throwing kegs and barrels, carrying objects like hussafel's stone (sp?), carrying heavy shit in your hands and arms and picking shit up from the ground for fairly high reps are much more likely to be things you may come across in real life.
Powerlifting isn't that functional, especially when it is equipped powerlifting as opposed to raw powerlifting...