Reyjohn Carlo

Brudda. Naruto is literally sealed in a timeless dimension. He can't train like Sasuke did.

Sasuke just fought limitless Code, a character stronger than Jigen, for an entire night, enough that Boruto was able to escape. Sasuke is factually stronger than Naruto at this point.

It's not seeking a narrative, it's literally just what the manga is telling us.