Anyone who has worked for a short period of time in an office, warehouse, assembly line, factory or fast food restaurant knows that there is a pecking order to be observed and adhered to. The human resources department does the job of reviewing applications, interviewing, hiring and ensuring the new hires are fully informed of their duties, responsibilities and benefits. Within this process, the new hires know who their supervisor or boss is. This is the first line of entry into the company and the chain of command is clearly established at this point.
The boss can go by many titles, from supervisor, to administrative assistant, department manager or Chief Executive Officer, but the main thing is that everyone in the organization reports to someone with a higher position and greater responsibilities. An assembly worker would not go to the CEO to request flexible working hours or a salary increase, he would discuss these issues with his boss who has been assigned the responsibility of keeping the work flow going while accommodating changes. The pay structure may be set from the top down and there is nothing an assembly worker or his boss can do about that unless the department's budget includes this option. Even with that last scenario, the budget is set from the top and flexibility is minimal in most situations.
The CEO is responsible for meeting and pleasing the shareholders and any disruption to profits will be blamed on her inability to lead or put in place competent employees capable of keeping their department running smoothly.
Structure creates order and makes the various duties assigned to a multitude of employees manageable and clear to all involved.