She isn't a killer and knows that there are people in Arcadia Bay who don't deserve that fate. It also allows Max to save people such as Kate, who appears at Chloe's funeral. It is worth noting that David does survive the destruction of Arcadia Bay and appears in Life is Strange 2. David will say that everyone he knew and loved, including Chloe's mother Joyce, perished in the storm. If Arcadia Bay is saved, he and Joyce will separate, but still keep in touch with David hoping to one day make amends.