My understanding of
@TaliesinSkye 's argument does not speak to the question of intelligence, it speaks to experience. Syllogistically, I think it would go:
1. As a rule of thumb, it takes about 10,000 hours to become expert at a skill.
2. Social interactions is a skill.
3. Therefore, it takes about 10,000 hours to become expert at social interactions.
The same would apply to politics, and those hours would have a partial but not complete overlap with general social skills.
Teenagers, especially ones who have spent the large majority of their hours learning combat skills and chakra use, have not had enough hours to master the social and political skills. They definitely have not had the same number of hours as a 50-year-old adult who has been a Clan Head for 20 years.
To preemptively respond to a few points:
Q: A teenager can be very smart, even smarter than an adult, and that will help them learn faster.
A: Absolutely agreed. However, Naruto is going to be competing against people who are as smart or smarter than he is.
Q: Well, Naruto has Shadow Clones and doesn't get Clone Sickness. His prime body may be only 15, but he's had the opportunity to acquire decades worth of experience via his clones.
A: Are you sure he doesn't get Clone Sickness? How many clones can he make, for how long, and how often? Is learning via Shadow Clones a linear process or does the marginal value of a clone decrease as the numbers go up? What are you basing these beliefs on?
TaliesinSkye, have I accurately stated your view?