To show different stages of life as they move on with time for example you don’t turn 5 and then 27. It’s to organize the stages of life and dates and times. Because biographies are about a persons life and how they grew up or came to fame so putting it in chronological order would help organize the historical events of that persons life. I think but I could be wrong.
Answer:
It's subjective. Both sincere and insincere can be argued.