IPFS is very close to what you describe (Merkle trees! Globally-identified hashes!) but it doesn't claim to be a blockchain because it doesn't have a consensus mechanism, let alone a way to prevent double spends.
And that's ok! It's designed for different problems, like file system style blob storage. It's not about "whether something is a blockchain", it's about "what's the right tool for the job"? I see value in complementary decentralized pieces of file systems, databases, processing, and more.
IPFS is very close to BitTorrent entirely using magnet: links, which does indeed have something close to a consensus mechanism (everything is checksummed to the hilt).
> It's not about "whether something is a blockchain"
It arguably is when you call your post "Blockchains for Artificial Intelligence".
For this context it's really about whether or not it can prevent double spends. Currently, it can't. Though its protocol stack has a place for consensus algorithms to achieve CAP-style strong consistency; and the IPFS team is working on consistency algorithms.
> It arguably is when ...
Point taken. The post is about things that many people consider to be blockchains or at least blockchain-like; BigchainDB, Ethereum, and others are in that category.
And that's ok! It's designed for different problems, like file system style blob storage. It's not about "whether something is a blockchain", it's about "what's the right tool for the job"? I see value in complementary decentralized pieces of file systems, databases, processing, and more.