Because they want to write an objective account. They write true stories, so they need as much information as it is possible to gather. If they used only one source, it wouldn't be a believable, authentic, and true story. Opposing or contradictory views are a valuable piece of information to include in a biography. They show the controversies of an age, not just various personal accounts about someone.
Answer:
Born on November 29, 1832, Louisa May Alcott led a fascinating life. Besides enchanting millions of readers with her novel Little Women, she worked as a Civil War nurse, fought against slavery, and registered women to vote.
They both describe healthy habits and things you should do in order to be healthy.
They advertise the pros and how it would be affect to the consumer
