Even in hunting parties, aren't there leaders who need to resolve disputes or ultimately take on the responsibility to make tough decisions? Isn't the most experienced or best hunter the one in this role? I'm not sure how this maps exactly to a cofounder situation (unless, of course, there happens to be a parallel in the startup in question), but wouldn't it make sense for this hunting leader to become the elder?
Is it not possible for the single leader situation to be replaced by a ruling group? As long as these members continue to do some of the other work involved in the village/startup, it does not seem like it would become a situation where there are too many leaders and not enough workers. Of course, this assumes that the group can continue to reach decisions in a reasonable manner.
I'm not saying these situations could occur easily or frequently, but they seemed to fall outside the realm of your explanation while remaining hypothetically reasonable and workable.