The original thought with VIR was that it could be inserted early in the signal path and allow correction for all that happened along the way. But then people started to reinsert it along the way, and I believe, even just before the transmitter so that it could be used to adjust the transmitter. Of course, it had no relation to all the preceding distortions then, and became useless in a consumer set. I remember doing competitive analysis of a GE set some time after VIR had been around for a while, and much of the time you would prefer to turn it off.
[EDIT - I mean turn off the VIR - but maybe you would prefer to turn off the set too!
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