so there are a lot of issues why you see vibrations at steering and in body and when you brake. The brake vibration is easy to nail down, usually a warped rotor, uneven pad wear which may be caused by fault or seized caliper.
beyond that, most of the vibrations come from unbalanced wheels, flatspots if the car is sitting in lot for months, under inflated or over inflated or defective tires, loose control arms, tire rods and lastly alignment.
If the wheels/rims have visible damage or bent, it will also cause vibration but the dealer told thats the most easiest to spot out.
Without doing roadforce, dealer cannot tell the balance is the reason as the road force simulates who each tire will ride on the road with vibration or not.
If that is tested and taken care off, then control arms, misalignment can cause some level of vibration.
lastly, swapping tires front to back reduces the vibration if the front wheels are having some sort of roadforce issue and as you come to your next tire rotation schedue, the tire belts and inner working of tire should even out over time and be softer as your get it back to front again.