User blog comment:B214/Talk About What You Want! 2/@comment-24098614-20140509210930/@comment-1359322-20140510004442

Typical Otaku...or is it Jose now. ( =_=)

Either way to your question why Issei or Reincarnated Devils allowed a chance to become a Maou. Simple cause they are Maou, they are the leaders of the Devils, they would want a real Devil to be their leader not one that got reincarnated. Think about it like this, you're from America suddenly a Russian comes to your country becomes a resident and rised up to become the president of your country, do you think people would like that? No. It's the same logic, they aren't Devils from the start, so no one would be able to accept them to be leaders of something that represents their very existence.