The reason why naruto is the only one who can defeat obito is simple,
Obito and naruto are parallels with the same personality of never giving up and Believing in yourself,
When they both clash and fight, Naruto will win proving that Naruto's way is the 'good" way rather than obito's which is peace through power.
The one who chose the light while not giving up vs the one who gave into hatred and gave up on world.
Perfect way of ending a well developed character.
Obito and naruto are parallels with the same personality of never giving up and Believing in yourself,
When they both clash and fight, Naruto will win proving that Naruto's way is the 'good" way rather than obito's which is peace through power.
The one who chose the light while not giving up vs the one who gave into hatred and gave up on world.
Perfect way of ending a well developed character.