I think there is a question of terminology here, Blockchain is a concept, Cryptocurrency is an application of that concept.

I imagine there are few people on HN who hate blockchain, it is a useful concept and forms the basis for some very useful technologies i.e. Git version control.

I imagine there are a whole range of reasons for negativity toward Cryptocurrency/Cryptoassets on HN. Personally I think the enormous number of new ICO and currencies being made available is purely driven by greed and fraud. While I see bitcoin and other major coins representing a great new application of the technology, I think it's been over-hyped to the point where I just tune it out.

TL;DR: Crypto != Blockchain. People hate Crypto for many reasons.