Knowing how something works is unnecessary to specify it if you can just point. And we can point. The things we are pointing at can turn out to be important (on reflection). By reproducing them without missing plausibly relevant details we can establish a reliable analogy between what we care about (even if we don't understand what it is and why we care about it) and the reproductions. By getting rid of the details we risk missing something relevant, even if we can't formulate what it is more clearly than by pointing.