Thank you for asking the question. The only person who can really answer this is the writer. Are they willing to share their inner most self and be totally authentic? I think that would depend on where they are in their own journey.
A different way to answer this question is that I would imagine all writing is personal, as you are writing from your point of view, which is the sum total of all your experiences and life choices to date.
For me, I am as authentic as I am courageous. This means that some subjects I can easily write about and share, and others are more difficult for me. It is all about keeping myself safe and sharing what I feel able to.
I hope this helps?
Love and blessings,