The CEO has access to all the information and all the expertise generated by the company. For that reason, that person should have the final say in most operational decisions that are going to affect the company.
The CFO for instance may have access to all the financial information related to the company, but the CFO isn't usually briefed about activities unless they have a direct non-speculative financial impact on the bottom line. And for that reason also, the CFO may have a particularly skewed perspective of the business.
The same goes for the officers in charge of marketing or operations. They may have access to lot of the information, but ultimately, their role limits them to their area and to a particularly skewed perspective of the business.
Obviously, there can be exceptions. Sometimes, the owner/largest shareholder of the company can have the power to replace the CEO on a whim, and for that reason, the owner/shareholder may be the real power behind the company. Or sometimes, the CEO will intentionally refuse to hear about certain things, to avoid potential criminal liability, or to avoid having to testify in civil cases. Or sometimes, someone else is being groomed to take over the CEO position.
But generally speaking, the CEO is supposed to be the center point of all that information and all that expertise generated by the business. And again, this is why they're supposed to have the final say in important decisions.