I completely disagree. Who is to say the 1/4 oz of weight your putting on the rear wheel isnt in the exact "wrong" place for the unbalanced carrier. Eg carrier is 1/2 oz out at point A now you dutifully balance your wheel and tire. Now you mate them up to install and unknown to you you slap the carrier and sprocket on exactly aligning the 1/4 oz wheel weights in the 1/2 oz heavy spot. You just made the "whole" package worse by 1/4 oz. Dont even get me started on a swinging chain that hits the wheel at a different spot every revolution.
I have had this same argument with almost every trackside tire vendor I know and NOT ONE has been able to dispute my argument. In my shop and 30 years of mounting tires I never balance rear wheels and never had an issue yet.
95%+ of a rear end vibration is chain, bearings, brakes in that order.