I get it to one extent. If you have an original to compare it to, you can more clearly see accurately an actor can reflect a particular personality, voice, mannerisms, etc. By why is that such a popular standard for actors at awards? Is accuracy the most meaningful measure of acting? Isn’t it more impressive in some ways to build an original character from the ground up?
I feel for actors playing real life characters. If they’re too uncanny and they nail the person, they’re only “mimics” and therefore, somehow not worthy. Conversely, if they dont represent the person with the same mannerisms and tone of voice etc, then they’ve “failed”.
If you take a person from history/real life, someone the public is fascinated by either because they are beloved or loathed, feared, and moved us some way, it’s a viable, easier showcase.
An original character is generally more difficult. Team a great character actor with a really great writing team and crew/Director, it can look like a ready-made ‘hit’.