Ordinal Inscription Size Limits

In a bitcoin-dev mailing list, Robert Dickinson expressed his curiosity regarding storing unlimited amounts of NFT or other content as witness data using the ordinal scheme. He raised concerns about the future disk usage of unpruned nodes and questioned whether unlimited storage is wise to allow for such use cases. He suggested finding a way to impose a size limit similar to OP_RETURN for such inscriptions. Dickinson thinks it would be useful to link a sat to a deed or other legal construct for proof of ownership in the real world so that real property can be transferred on the blockchain using ordinals. However, he finds storing the property itself on the blockchain nonsensical.Andrew Poelstra responded to Dickinson's query, stating that there is no sensible way to prevent people from storing arbitrary data in witnesses without incentivizing even worse behavior and/or breaking legitimate use cases. If "useless data" is banned, people would embed their data inside "useful" data such as dummy signatures or public keys. But banning "useful" data could lead to a pre-Taproot problem where constructing signing policies in a general and composeable way becomes impossible. In addition, Poelstra argues that although storing NFTs and other crap on the chain is toxic to the network, he doesn't see any principled way to stop this technically.Poelstra also notes that the Bitcoin fee market would become entangled with random pump&dump markets, undermining legitimate use cases and potentially preventing new technology like LN from gaining a strong foothold if people were storing NFTs and other crap on the chain.