https://anime.stackexchange.com/questions/43592/why-does-sasuke-consider-naruto-to-be-his-best-friend?rq=1 Perusing this question's answers just now, one of the comments stuck out as potentially grating:
'"to facilitate the underlying Asura and Indra plot" But wouldn't this imply that the author had that plot in mind from the very beginning? Is there proof of that?'