Let's look at this a little differently -
Scenario #1:
You install your bindings at home using your torque wrench, which in order to follow recognized standards, you have calibrated and certified on a yearly basis. Once you get to the hill a start riding, you realize that the stance width is too narrow. You get out the 5mm allen wrench that is provided with the bindings and attempt to loosen the screws. You quickly realize that there is no way in he!! that you can generate enough torque to break the fastener loose; now your are stuck either trying harder and potentially rounding-off the wrench or head, or your have to live with the incorrect stance width until you have access to your torque wrench.
Scenario #2:
As documented in other places, not all boards are made the same. As you install your new bindings, at home, using your certified torque wrench, you attempt to torque the screws to the value specified by the binding manufacturer. Before you reach that torque, you strip an insert. You are really pissed and call the board manufacturer, they tell you tough because you tightened the fastener to too high of torque value. You contact the binding manufacturer, they tell you tough because the inserts are not strong enough. You then vent your frustrations by logging into your BOL account and bashing both the board and binding manufacturers.
Scenarios 3 through ...:
Use your imagination
Scenario #138,924:
The manufacturer provides one wrench. Through their testing they know that when the average person tightens fasteners using the provided wrench, that adequate torque is generated 1) so that the fasteners do not loosen during use, 2) the applied torque does not exceed the shear strength of the insert threads, 3)...