People are stashing irrevocable child porn links, dox, copyright infringement, and leaked state secrets in the blockchain

By design, data placed in the blockchain is visible to everyone in the world and can never be removed; everyone who mines bitcoin makes a copy of the blockchain, and so any illegal content stashed in the blockchain ends up on the computers of every miner. Many governments make possession of certain materials -- state secrets, images of the sexual abuse of children, copyright infringing materials etc -- a civil or even criminal offense under any circumstances.