Take him away then. Imagine he just vanished. Took a sabbatical, didn't say where he was going, and just disappeared for a year.
What would happen? Things would function. They'd probably be fine for the first couple months, and they might even pass their first quarterly earnings without anyone noticing he's gone. If the department heads all were quiet and didn't notify the shareholders, things would seem completely fine.
But then the next quarter comes up. Money shifts around a little bit creating a small deficiency here, and a surplus over there. Department heads start to assist each other towards shared goals which may be detrimental to other departments.
Tribalism starts to take hold. Each department head is now their own top dog, and some will start to breed a culture within their areas where they believe they are absolutely more critical than other areas. Some individuals may start to actively sabotage the other departments if they feel it serves to benefit their own dept.
Without a CEO, you no longer have a company, you have a community of companies that are in direct competition with each other.
This doesn't mean the individuals within a company are unimportant. They get plenty of recognition within their own circles, but when you're talking about money, there's a reason the CEO is the focal point.