Comment by aforwardslash

I'd argue that PoS/PoW have nothing to do with the blockchain concept, and instead are a way of building virtual currencies on top of it. The easiest way (for me) of thinking of a blockchain is a distributed merkle tree (or a patricia trie, if you're into ethereum or whatever), with a consensus mechanism. That's it. What you put there is your own responsability - so if you decide to create a virtual currency and either reward work or reward possession, its up to you - but that's on top of the "blockchain" concept. And I've actually came across some pretty valid use cases - one good example is that blockchain could be used to enhance resiliency on systems like certificate transparency - that are already a centralized, versioned sparse merkle tree.