An idea I'm coming around to is that the "great men" dynamic Feynman is talking about isn't actually a property of individual people, it's situational.

Like, being humble, competent in your field, mature enough to actively listen to other people, etc, all help. But there are also more subtle factors like compatibility, company culture, project parameters, etc, that are also necessary to have that dynamic where everybody cooperates in discussions.

Getting those subtle factors to align is hard, sometimes it's down to conditions you can't control, and it's definitely not as simple as "just" getting great people in a room.