Old commercial guys liked me used Polaroid, yes, but we certainly didn't base our exposures off of it. It served several purposes, mostly for client cooing and composition discussions. I never once based an exposure off of it, nor do I know any contemporary who did. I suppose it may have provided some validation of an exposure, if one felt like doing the math, but it was different enough that mostly you spent time explaining that the actual trans wouldn't look like the Polaroid.
I could see a d cam used as a Polaroid, what I can't see is basing exposure on something with about three stops of latitude when your exposure on film could fall anywhere in that three stops or more and still be more appropriate to what you might want. That's possibly giving up an awful lot of printing range. Its like looking at the possibilities through a crack. I can't explain it better than that.