They are very much linked to one another. If BitCoin didn't offer anything novel over and above other media of exchange, like fiat currency, its value would approach zero. Its differentiating quality is the blockchain and peer-to-peer distributed concensus.

You could have a cryptocurrency without a block chain

Perhaps, but then you'd need to solve the problem of trust-less peer-to-peer Byzantine concensus a different away, using a different mechanism. And that's exactly why the blockchain is novel.