Your scenario leads to the disenfranchisement of lesser-known voice talent, since they cannot take on work that Top Talent has rejected if they happen to resemble(nobody here has seen their doppelganger before? How unique is a person? 1 in 5 million? Then there are 36 million of that type in just the United States alone). Perhaps it's time to re-evaluate some of the rules in society. It's a healthy thing to do periodically.