Your post was so Biased (especially the naruto bullets), it's not even funny. Answers in Red btw.
He had to train his MS skill first, fight 5 Kages with
0 intel (> Pain), and he had to train his Sharingan for +3years before unlocking MS, in contrast Naruto was traveling the world with his teacher stalking women
Even though Itachi wouldn't kill him Sasuke still would've suffered fatal wounds if he didn't take the fight seriously (i.e : Amaterasu), Pain was nerfed than Itachi btw.
And it was a big deal for Sasuke to train under Orochimaru because having his body taken would have meant all his efforts were for nothing, he grew a pair to reach his ambitions, Naruto needed support for crying over his friend.