The thing you have to remember is that Hitler was relatively young when he wrote Mein Kampf he was in his mid 30s and it was more then 10 years before he came to power. Whilst he never repudiated the more extreme points in the book he didn't speak of them once he became a "respectable" politician. So most people thought that Mein Kampf was the product of a youthful mind and that Hitler had changed in the years since. They thought he was actually embarrassed by the book.

Hitlers Dark Charisma Laurence Ress

The Coming of the Reich Richard Evans.

Do you have any examples of where that is said on hand? That would be helpful for whoever ends up answering your question.