More like "Don't try to shoehorn your existing knowledge into that thing you are trying to learn and use; it may or may not fit but isn't supposed to". That absolutely doesn't prevent you to use your knowledge as stepping stones to understand the new thing.

> Wait, the advice is "ignore your past knowledge and experience and start from nothing" ? That strikes me as terrible advice.

well, with knowledge i hope there is wisdom as well to apply it in a manner befitting the context.