If you go to Vegas, you can go to a wedding officiated by someone who looks like, sounds like, and acts like Elvis Presly. This is available to anyone. You can get the same actor to do the same simulation for another purpose if you're willing to pay for it.
The biggest difference that I see is that technology has made the simulation cheaper and easier.
And these people are known as "Elvis Presley impersonators." They don't pretend to be some obscure person you've never heard of, for very obvious reasons.
The biggest difference here is obviously one of scale. I don't think ScarJo would be threatening to sue you, the individual, if you did a voice impression of her for a talent show or a friends wedding.
The biggest difference that I see is that technology has made the simulation cheaper and easier.