

Because the service is going to hash whatever password you provide. If you sent the hash itself, it would hash it again and get a non-matching result.
You’d think that having those hashed values might help, but it doesn’t really (as long as other best practices are in place). Ultimately having someone’s password is used to impersonate them, which means using the same front end to the service as everyone else.














The main difference between encryption and hashing is that hashing only works in one direction, while encryption is meant to be decrypted later. With hashing, you can create a special combination from a password or something, then you can test for that same initial password by using the same hash process on new input.