It's tradition. Tesla's autobiography is also similarly... nuanced.
He claims he routinely ate rocks, iirc, among a number of other incredible claims. His tone also sounds as if he cares about convincing the reader, which is a sign that an author might care so much about persuading the reader that they might distort certain truths to be more convincing.
No, Tesla claimed Tesla ate rocks in his autobiography. And many more interesting claims, like that Tesla always knew his own weight to the pound, and quit smoking in a day by deciding to. (The smoking claim is actually the most believable, but it's mixed in with silly claims about eating rocks and "abs like a crocodile". I'm serious.)
It's a wonderful book and really worthwhile, but it's not an accurate representation of his life in any way.