I'm skeptical that you get a view of the system through BDD tests better than with somebody walking you through the product. The person can explain the domain,

I'm skeptical that you get a view of the system through BDD tests better than with somebody walking you through the product. The person can explain the domain, the context, the subtleties, skip the not-actually-interesting-parts, draw things for visualisation, etc while adapting the explanations to the fact that they're talking to a newcomer: the tests do none of that (but maybe I've never done BDD properly)