I guess that’s one way of looking at it. She was 20 when she got the Star Wars part. She was chosen for her type, not for her range. She never became a great actress, but she was a talented writer and monologist who did a lot with her troubles and her family’s to make herself and other laugh. Many of her problems may have been related to her being bipolar, and she did much to make that condition better known.
She was also known for being a “script doctor” - re-working scripts for several well know movies, some without accreditation and writing for some sitcoms like Roseanne.
I recall an episode of Th Big Bang Theory with guest start James Earl Jones playing himself. He meets Sheldon who wants Jones to appear at the Comicon Sheldon wants to start of his own, and Jones turns out to be a bit of a party animal and takes Sheldon on several adventures including pranking Carrie Fisher who also briefly appears.
Surprisingly this was the first time Jones and Fisher had ever met in person. Upon meeting Jones, he said she ran up to him yelling “Dad!!!”
https://www.youtube.com/watch?v=XjDd4hWny60
Seems that is a common affliction of celebrities: Margot Kidder, Patty Duke, Linda Hamilton, Mariah Carey, Mel Gibson, Demi Lovato, Russell Brand, Brian Wilson (Beach Boys), Kurt Cobain, Jimi Hendrix, Ernest Hemingway, Virginia Woolf, Ted Turner, Catherine Zeta-Jones, Vivien Leigh, Frank Sinatra, Sinead O’Connor, Jean-Claude Van Damme, Jane Pauley, Amy Winehouse, Selena Gomez, Kanye West, Margaret Trudeau, Richard Dreyfuss. Even Winston Churchill is cited as being bi-polar. You have to wonder if they were bi-polar before they became celebrities, or was it their exposure to that world and lifestyle, that attributed to their bi-polar diagnosis.