from my years of training experience I can say with 100% certainty that the old adage is true and that the later does indeed make an ASS out of YOU and YOUR CLIENT.

This isn’t what you want as a trainer or a client.
Am I correct?

The Functional Movement Screen is the greatest tool you can have in your arsenal as a fitness professional.
When I screen a client, I am able to have a concrete plan of attack for my programming.  Thus allowing for the greatest client success, which makes both of us happy.

Sure pushing, pulling, squatting and lunging are movements that are highly encouraged.. but without proper mobility and stability these exercises cannot give us the core involvement that we need to be efficient and progressive with our workouts.
When our core is firing to its potential and our movement patterns are symmetrical, anything and everything is possible.

A carefully created program is good, but a specifically sequenced warmup can make that same workout GREAT!

This is where I think many trainers as well as those of you who workout, mess up.