Grazdanin Mikhail Timofeyevich almost certainly did not have the AK-47 design spring full-blown from his forehead. It is a robust, reliable design that lends itself to mass production; definitely one of the most noteworthy guns of the 20th century. Mikhail Timofeyevich, unhappily, is also one of those not-too-uncommon people who works as part of a team but claims sole credit for success himself. Max is dead on target with his assessment of why this was allowed to happen.
My wife and in-laws are from the former CCCP and they are scornful and disbelieving about such stories. The Soviet government lied to the world and it lied to its citizens, it even lied to itself. For some, like Mikhail Timofeyevich or Vasily Zaitsev, it was of benefit to allow a myth to be built around them.