So, is blockchain therefore even needed? Why should you even "first you download the internet" (or even a subset of it)? I just want to watch some cat videos.
Confirming data integrity and origin is already solved - thanks digital signatures and checksums.
The only thing blockchains add is a strict ordering.
So someone can now sign a message A saying "I give this picture to X" and everyone will know that any future message B from that person saying "I give this picture to Y" is "invalid" because everyone agrees that message A happened before B. Anyone who downloads the whole blockchain can see this.
Well, as long as everyone agrees to believe that blockchain.
In case my bias wasn't clear enough: no, they're a solution looking for a problem and right now the biggest problems they're targeting seem to be a lack of grey market money laundering and pyramid schemes.
Confirming data integrity and origin is already solved - thanks digital signatures and checksums.