Board Thread:Wiki Discussions/@comment-3238846-20140422105553/@comment-732150-20140427180343

Naruto's situation is the exact same as Roshi's. Roshi's use of Lava Release from day one was attributed to Son, using Son's ability. For all we know Roshi has no fire or earth chakra on his own, yet he is listed as Fire and Earth Release user as well.

Not to have someone who uses Lava Release as a user of earth and fire is like having a Rasenshuriken user not to be listed as a Rasengan user.