Velocity alone certainly doesn't describe it at all. The only reason it's used is because we think in terms of an object moving and the end result of it. We see a car colliding into another car and can see the damage. We observed before the collison that both vehicles were moving. We therfore conclude that because the cars were moving, at whatever speed, damage occurred - aka, the more speed, the more damage.
To say energy doesn't matter is incorrect. The impact velocity is a result of how well the energy was conserved from time = 0 (at the muzzle) to time = n (at impact).
The pic of the side of the cow elk shown in the .243 use on moose thread clearly demonstrates the effect energy has on ballistics performance. If all the energy were retained in the bullet, there would be no wound channel other than a pencil sized hole. We want the energy of the bullet to dissipate in the most efficient manner. Part in deformation (fragmenting), part in tissue disruption, and the remainder carrying through to exit.
It being discussed "ad nauseum" here causing "rabbit holes" suggests a lot of strong but misguided opinions being held...