I wouldnt agree with the notion this is essential
Where I would suggest it has value is in owners who have high standards on finish and wont accept the smallest blemish like some orange peel. Those orange peel hard core customers will expect it flat sanded back and all paint corrected. Also, small things like if an owner hasnt maintained the car much and the headlights are faded then swapping one side, far easier to have choice of repair force a buff compounding and polish of the remaining headlight so that both headlights perform in the same ballpark etcetc
Yes yes all this "might" be argued post the fix in an insurer appointed repair but often its a major hassle and take weeks and weeks additionally just to get a slot to do that sort of work again. Never except delivery from an insurer if its not good I say. More leverage to leave it there.
Its really not the panel shops fault here as an industry - insurance companies have put undue pressure on them and are constantly at them on the smallest costing variances. Therefore some shops like my associates in response just chuck a well dear insurance companies on ya bike, we dont need you.