Also keep in mind the importance social and political skills. Someone who is both top talent and the hardest working can be taken down if a higher up doesn't like them. So when people like that refuse to learn social and political skills, their only hope of success is to start their own venture, but even then, they will lose all their best talented people if they don't learn some downward direction social skills, just as they won't move up in a larger company without upward direction and teamworking social skills.
Sometimes talent requires additional social skills to compensate for resentment from less talented. Being unintimidating can have the opposite effect and bring the political tide in your favor. Depends on the context.
I started a Toastmasters group from scratch at my last office and served as president, and our club did exceptionally well for a new club, reaching Distinguished Club status during our second year.
This is noteworthy as I have almost zero natural talent in public speaking. I found it hilarious and eye-opening when one guy told me that one of the reasons he liked our group so much and me as president was because I was so unintimidating as a speaker.
I have had much less political success in areas where I am significantly more talented than I am in public speaking.
In opposition to the forces of talent and hard work, political forces favor the likeable and the average. Case in point: GW Bush.
There are exceptions, also, but those forces exist.
The ideal is to be talented, hardworking, likeable, and unintimidating (at least on the way up). Edit: On second thought, maybe only unintimidating to higher-ups, as demonstrated by XNTJs? Not sure.
Having said all that, I also agree that for the most part, only a threshold level of talent or intelligence is required in most cases. Additional talent is only useful at the leading edge, and only in limited amounts.