How does incorporating marketing,operations,admin. & hr to the roles of finance manager directly affects your company's goals?

According to me a finance manager should me made aware of the major functions of the company's marketing, operations, admin & hr departments. But, incorporating these roles along with the current roles of a finance manager will adversely affect in achieving the company;s goal because the each domain specialist will not be able to perform with their own expertise and the entire burden lies onto one shoulder. Also, this creates a lot of dependency on a single person or a bunch of people for various functions.