Saying that something is ineffable and saying that nothing we can say is meaningful without the exact same shared experience are rather different things. To use your own example, comparision is possible - so we can imperfectly describe chocolate in terms of sugar and (depending on the type) bitterness, even if our audience has never heard of chocolate.

Conveniently, this allows us to roughly fathom experiences that nobody has ever had. Playwrights, for example, set out to create an experience that does not yet exist and prompt actors to react to situations they have never lived through, and through their capability to generalize they can imperfectly communicate their ideas.