So I had a thought. Kakashi and a few others were quoted as saying bloodline limits can't be copied even with the Sharingan because they're tied into the genetics of the user and you can't mimic DNA with the Sharingan But Kakashi has just learned how to warp himself with Kamui and how to bring other things (like the 8 tails) back from that other dimension. Did he copy Obito's use of Kamui? Because realistically since they have the exact same eye technique, Kakashi should have been able to copy how Obito uses his Kamui (He's not copying the bloodline limit, since he already has it. He's just copying a new implementation of the technique).