That's how I envisioned the work to be done, however, when you go to a shop, sometimes you suspend disbelief because they are "the pros".
In my understanding, there are only really three things that need to be done to fit and align the boot properly -- assuming that the shell is fine as is....
1) Get custom footbeds -- this is to reduce the pronation that usually occurs when flexing. It ensures that the foot remains in a naturally strong position. Footbeds need some give for the lateral balancing movements of the ankle to remain effective -- else the balance control shifts from the stabilizing muscles to the prime movers -- which is not what they are intended to do. If you are balancing mostly with the prime movers, it is likely that you are often out of balance. Balance requires subtle, not gross movements.
2) Align the cuff so that it does not alter the natural angle of the tibia entering the ankle. This is the strongest position for the ankle. Why? When the stabilizers of the ankle have much work to do, the prime movers (calf/shin muscles and even quads) will NOT operate effectively. There is a failsafe feedback mechanism, best explained by a weightlifting analogy built in to the body:
Many people fail to lift a weight, not because their prime movers are insufficient, but because the stabilizers cannot hold the weight in place. eg. A hockey player, whose name escapes me, could bench press sets of 245. He could not bench more. He strengthened only the rotator cuffs in the shoulders with a 6 week program. He did not bench at all, so there was no added chest strength. At the end of 6 weeks, he could bench press sets of 290. Why? The shoulders could now keep the weight safely in balance. The prime movers did not receive the "abort! I'm going to drop it!" signal from the stabilizers failing to keep the weight in balance and so could effectively do their job.
Same case with the leg. If the ankle is in an unstable position, the function of your calves, shins and even quads will be compromised. A stabilized ankle will enable the skier to produce the highest leg forces. A stabilized ankle is one where the stabilzers are most effective, and not taxed unnecessarily with a boot cuff alignment that forces the tibia one way or another. Simply put, if the ankle is rolled to one side or the other, you can't push as hard as if it was in it's natural position.
In the worst case, you can hurt yourself trying. Damage to the ankle and knee can result. Also, if too far out, the outer quads are used over the inner quads, which will pull the knee cap to the outside, so it will no longer track in it's groove properly. Result: swollen knees, and the possible start of knee instability. Get the cant right.
3) Canting shims: Used solely to move the knee over the foot into it's strongest position. Again, weightlifting says that the knees must track over the toes for the lifter to lift the heaviest weight. Ideally, that's between the big toe and first little toe. In this way the forces experienced by the knee are directed solely through knee, and have no component that will move the knee sideways. The lift will always be aborted if the knee collapses/moves sideways. Same for skiing -- the forces should be directed straight through the knee, not sideways, so that the maximum effort from the quads may be realized.
Of course you could actively HOLD the knees over the feet, but the effect on bowlegged people would be to increase the bite of the inner edge when skiing in a neutral position. Knock-kneed would have more outer edge bite. This is contrary to the goal for the skis to be flat to the snow in neutral.
One gotcha: It may not be possible to move the knee to the ideal spot over the boot and remain strong, as the amount of movement will also effect the angle of the thigh bone's entrance into the pelvis. Too much movement and the stabilizers of the hip will start issuing abort signals when taxed... It has been suggested that 3 degrees of movement of the knee via canting shims is the upper limit of effective movement before compromising the alignment of the thigh bone into the pelvis.
How'd I do?