Bad isn't the right word here. It's a bad cryptographic hash, sure, but a hash doesn't necessarily need to be cryptographic to be a hash. P-hash for finding sim

Bad isn't the right word here. It's a bad cryptographic hash, sure, but a hash doesn't necessarily need to be cryptographic to be a hash. P-hash for finding similar images; sounded/metaphone for similar English pronunciation; crcs, cityhash, siphash, &c for fast checksums and hashtables; and location sensitive hashes like simhash for "close matches" for spam filtering and content aggregation all have a long history of being good and useful hashes without being cryptographically secure.