[RandomLensman]

In the generic form, blockchain/DLT cannot solve the double spend there either. Selling a picture for a token does not magically delete all copies or makes it impossible for me to sell it again (yes, someone could look in some blockchain, but that might not even deter another buyer - even fake goods trade).

Basically, for on-chain assets, a blockchain solves double spend and also ensures that on-chain funds/assets are correctly delivered (malicious attacks aside). This also exists outside of blockchains, for example in payment vs payment settlement in FX. Banks created CLS precisely to avoid having one part of an FX transaction settle while the other was still outstanding - so other ecosystems with immaterial goods and risky settlement found other solutions/created their own "middle man mechanic".