Yeah it's amazing how much misinformation is out there. When I bought my first BP I had them tell me about the same things and they sold me a dang aboreal cage! I'd done some research before I bought her but obviously not enough. There was even a guy there in the store that was telling me that he had a BP for 4 years and they have to have both UVB and UVA light and vitamin supplements. I should never have listened to him because he was saying that his BP died on him after he'd had her for 4 years.
Of course I know a lot better now and all my snakes are thriving without any vitamin powder lol.