There are ways of doing this that aren't trivially parallelizable for an attacker: https://www.gwern.net/Self-decrypting-files https://www.gwern.net/Self-decryp

There are ways of doing this that aren't trivially parallelizable for an attacker: https://www.gwern.net/Self-decrypting-files https://www.gwern.net/Self-decrypting-files. (Of course, the criticism still applies if the adversary is faster at whatever single-threaded operation you build the timelock on.)