That sounds awfully reductive. While it's obviously true that many blockchain-based businesses are/were just trying to cash in on hype alone, that doesn't mean that ALL ideas involving a blockchain are bad.
I'm sure there exist a few rusty metal sewage snakes in need of lubrication, but that's not what most people are selling snake oil for.
Not only does attaching to it act as a fairly reliable indicator of fraud or cluelessness, but it also means that you'll be constantly wasting your time deflecting suggestions to copy practices which are illegal, unethical, or just technically unsound from the majority of other 'blockchain' based ventures.
He brought up an example whereby some user could hide something very illegal within the encrypted data.
To be honest, I don't know enough about block chain or the blockchain economy, but the idea of hiding data/URLs related to very illicit content definitely makes me think it could be abused. Especially since decryption would be necessary to uncover the abusive usage (i.e. the concealing of illicit content/URLs to illicit content)