Who thinks otherwise? Minato stomped him and took the Kyuubi from his control, if anything is true its that Kurama beat him. Even that is not a fair statement.
Obito vs Minato is kinda same as Sasuke vs Diedara....so if you think that sasuke (won)killed diedara then you must also admit that Obito (won)killed Minato.....i'm not saying anything on this matter...both are my favourite...i'll be biased if i said otherwise.
and don't tell me introducing kyuubi was unfair....everything is fair in a fight, and i don't think Obito gives much shyt about honour.
and you don't see Obito and Madara complaining about the 2 vs Zerg (entire shinobi world)
While it's true that Minato won against Obito back then, Obito suffered way smaller losses. Much like Madara claimed he was spiritually victorious against Hashirama, the same can be said about Obito.
What's more, Minato had troubles defeating 14-year old Obito. Current Obito is on a whole different level.