Why do companies have co-CEO’s?

I have often wondered why large companies opt for 2 or more co-CEOs. There are numerous examples in recent times:

Oracle – Safran Catz and Mark Hurd
Salesforce – Marc Benioff and Keith Block
SAP – Jennifer Morgan and Christian Klein

My research shows that this has happened earlier at Wholefoods, Chipotle, Samsung, Deutsche Bank. It was largely uncommon until more recently with some large companies adopting this style. The first thoughts that come to my mind on the Co-CEO style are all disadvantages:

i. Conflict of visions / strategy
ii. Confusion amongst clients
iii. Confusion amongst staff with a division of power / command
iv. Conflict between core teams of the co-CEOs
v. Need for cross reporting to each other / slower decision making
vi. Stepping on each other’s toes
vii. Not enough authority to act independently
viii. Complexity with the Board’s assessment of the Co-CEOs (especially when things go downhill)

I had a struggle and had to think harder for advantages:

i. Effective for startups with Co-founders as co-CEOs
ii. Good short-term arrangement while grooming a new CEO while the old one prepares to step down
iii. Effective for Husband-Wife owned companies or people who have a great bonding
iv. Complements different skills / strengths
v. Balances power / reduces single point of failure (one could counter argue this with the existence of the board / second line leadership)

One might argue it works at Oracle and Salesforce. My counter argument would be that it works in Oracle because there is the shadow of a super CEO Larry Ellison. It works at Salesforce because Marc Benioff and Keith Block apparently have a friendship and trust since the 80s. We must watch what happens at SAP in the future although it seems to have worked fairly in the past.

I am not a big fan of the co-CEO structure. Imagine a country having 2 Presidents or 2 Prime Ministers or a sports team having 2 captains or 2 managers. Would it work? May be not. The disadvantages of co-CEOs far outweigh a single CEO structure in my view. There are far too many examples of success with one CEO / one leader at the top. It’s a time-tested structure. I like the one CEO leading the company being the first amongst equals.