Maybe we'll see a solid societal use case for zero-knowledge proofs here, establishing one had a set of documents at a given date without revealing them.
you can just write a doc with your proof/idea, hash it and post that hash on twitter
Yes, you can. So maybe we'll see an adoption of that paradigm, or another. The value of a ZKP is that you can optionally prove some facts up front about the file, whereas a normal hash is all-or-nothing. You can't reveal part of the information because you need the entire contents to properly verify the hash.