Joseph Meehan wrote:

....
Yet isn't the spring's function to neutralize this force? The spring
overcomes this to negate the user or mechanical opener from having to
deal with the full weight and inerta of the door.

Well it means it does not have to deal with the full weight of the door,
but the inertia is still a possible problem. ...

It'll divide w/ the relative weight carried by the spring as well...as
far as the motor knows, the door only weighs as much as the weight not
carried by the springs in the fully closed position.