According to former Mars executive Alfred Poe, PB Max was discontinued due to the Mars family's distaste for peanut butter, despite $50 million in sales.[6] wikipedia
This is true. The Mars family grew up in Britain where peanut butter is nowhere near as popular as it is here. They prefer hazelnut. For the longest time Mars didn;t use peanut butter in anything.
This is from the book Emperors of Chocolate, history of Hershey and Mars but candy industry in general. Great book, I read it like a novel.