Board Thread:Naruto Discussions/@comment-9782468-20151224201414/@comment-25122992-20151226151400

Obito's left Sharingan was taken away and transplanted to Kakashi, who stayed alive and well. And Obito's right half of his body got crushed by huge boulders, it's hard for a normal man to believe something could remain from it (even Madara admitted that his right eye survival already was a miracle). So this sole valuable thing in Obito's body was thought to be half taken from him/half destroyed, that's why there was no point in searching for his body (if someone searched for it at all).