Why Obito being Tobi doesnt make sense...
1. Tobi monitored and founded Akatsuki through Yahiko's motives, they were like 17-18 here(Hanzo said they were young kids), during this time I believe the Kyuubi attacked Konoha(Sannin would have been there if they were there).
2. Tobi and Madara worked together ever since the Senju vs Uchiha war started until the founding of Konoha.
3. Tobi has vast knowledge about genetics, shown by his outstanding collection of Sharingan in his lab and genetic engineering of Hashirama Cells to recreate Mokuton in Madara and Zetsu.
4. Obito and Kakashi were close friends, Kakashi was a Jonin at a young age and its shown Jonin is supposed to recognize chakra patterns within different people to identify them, if Tobi is Obito, would'nt Kakashi recognized with Sharingan.
And Minato would also recognize this chakra if he was Obito, his own student.
5. Obito's timeframe with Madara is far off. The potential year difference between them is probably 30 years, unless you crazy enough to think Obito was there before the founding of Konoha.
And just because there warping jutsu is the same doesnt mean he is Obito.