He explained theory to Obito. As for the Inyoton and such, he used it in the real world, when he infused Black Zetsu into that White Zetsu.The experience and knowledge he gains from the Genjutsu world is real once he's in the real world. Unless you want to explain to me how Madara was teaching Obito about In'Youton, Rikudou No Jutsu, Uchiha Kinjutsu and was passing him knowledge about IT? He did all that via the Genjutsu.