A lot of formalism around real laws and real money exist to make word of mouth scale. It's why people pay money accepted by everyone in their society, why they enter written contracts - of the type they can expect the court of law to treat as valid, if a dispute escalates to the point of involving third parties.

Can't shake the feeling it's just the next chapter in the story of cryptocurrencies rediscovering the hard way the last 10 000 years of social development.

IPFS, as a P2P system, only contains the files individual users are hosting. There's no fundamental obligation to rehost other people's content - but there are various incentive schemes[0]. The address itself is a hash of file contents, so if someone were to reupload the exact same (bit-level identical) file to IPFS again, it would appear on the network with the same hash. The limit to long-term availability of any given file is whether anyone who has it is willing to keep it in the network.

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[0] - For one, IIRC, there was some automated caching/mirroring of the files you pull using an IPFS client (not IPFS->HTTP gateway), to ensure popular files will get mirrored around the network for a while. Secondly, the team also started developing FileCoin, whose purpose was to create a scheme in which people could get paid for putting their spare storage on the network, which would be used to replicate files on IPFS. I don't know if they managed to get it to work.

My interest in IPFS started to diminish after I saw the team getting very involved in cryptocurrency world. I only care about IPFS for the P2P, content-addressable storage layer - and they kept talking about things related to Ethereum. So I stopped paying attention.