Well, I think it might be an inaccurate statement.
The coffee itself has tangible value (for a while, while it is still hot and fresh, at least - that tangible value is transient). That does not mean that someone taking bitcoin to give you coffee means the bitcoin represents tangible value, any more than it means the coffee represents bitcoin. There was an instance where I literally sang for my supper - I exchanged a song for a meal. Does that song now represent tangible value? Hardly.
Lacking something like a gold standard, forms of currency represent tangible value only insofar as we all agree they do. Sure, maybe you can buy a coffee. But can you buy all your groceries and pay your utility bills with it? Then, I question how tangible a value they represent. Their applicability was still too undependable, I'm afraid.
Of course, "currency" isn't actually solidly defined in the first place, so opinions will vary.