Seems everyone on Hacker News has already forgotten about Anthropic’s amazing new watermarking algorithm. You don’t need to look any further to understand why it writes so awfully - it literally swaps words programmatically all over the text from the result of a hash function…
This was an issue before watermarking was publically announced. I'm also not an expert, but aren't bits of a hash indistinguishible from uniform randomness?
Depends on the particular hash. Some hashes are designed to produce similar outputs when the input data is similar (for example, SSDeep). I'd imagine hashes designed to survive light copywriting would also not be entirely indistinguishable from random.