There's one confounding factor I wonder about. If a company, at some point, has a great long serving CEO or founder, that person will have great influence on c

There's one confounding factor I wonder about. If a company, at some point, has a great long serving CEO or founder, that person will have great influence on choosing their successor. They will also have influence on who is on the board of that company. So there may be a virtuous circle called "culture" at that company. Could that not make it look like the CEO statistically doesn't matter?