How do chain of command and unity of command coordinate organizational work?

"An organization with a well-defined hierarchy has a clear chain of command , which is the line of authority that extends from one level of the organization to the next, from top to bottom, and makes clear who reports to whom. The chain of command is shown in the organization chart and can be traced from the CEO all the way down to the employees producing goods and services. Under the unity of command principle, everyone reports to and gets instructions from only one boss. Unity of command guarantees that everyone will have a direct supervisor and will not be taking orders from a number of different supervisors. Unity of command and chain of command give everyone in the organization clear directions and help coordinate people doing different jobs. Matrix organizations automatically violate the unity of command principle because employees report to more than one boss, if only for the duration of a project. For example, Unilever, the consumer-products company that makes Dove soap, Ben & Jerry’s ice cream, and Hellmann’s mayonnaise, used to have a matrix structure with one CEO for North America and another for Europe. But employees in divisions that operated in both locations were unsure about which CEO’s decisions took precedence. Today, the company uses a product departmentalization structure. Companies like Unilever tend to abandon matrix structures because of problems associated with unclear or duplicate reporting relationships, in other words, with a lack of unity of command."