This is a terrible analogy. A house is a finite asset which only one person can occupy at a time. An infinite number of copies of a JPEG can exist. The city/state has the power to enforce property rights. The blockchain does not. The NFT is just a note in a ledger somewhere which others may or may not respect. It's really quite simple.

There's so many terrible analogies associated with NFTs and blockchains too. It all comes from their confirmation biases. They're already too invested into it to back out. It's too easy to become blind to any valid criticism, so might as well come up with as many analogies as possible to attempt to gather more recruits and justify their decisions.

It's much more like "buying a star" website.

A better analogy would be that the blockchain is a filing cabinet. A deed has the force of law because the city/state is prepared to use violence to enforce the ownership claim inscribed on the deed. What authority is going to enforce your NFT?

All of the people that use the blockchain as the source of truth and authority enforce it. The question you're asking is literally the same as "what gives bitcoin value". The answer is everyone who believes it has value. Why is TSL/SSL an agreed upon encryption scheme? Because people agreed to use it and you're excluded from access if you don't.

When twitter integrates NFTs and requires you to sign a proof of ownership to set an NFT as a profile picture (with a verification check mark), this effectively signals that twitter is enforcing the NFT. When facebook does the same, it signals that Facebook is enforcing the NFT. When Spotify integrates NFT licensing, they will be enforcing it.