There's really not much rational for capping passwords at anything beneath 256 characters.
256 characters makes for a fairly sizable passphrase, and doesn't represent a substantial hit on storage space. In reality, even if they were stored as encrypted binary/base64 in a nosql file system of structured data files, 4096 is pretty much the de-facto floor for disk space occupied by non-zero-byte individual files on most modern file systems.
...variable data size being a concern in cases where the transformed value is encrypted rather than hashed.
256 characters makes for a fairly sizable passphrase, and doesn't represent a substantial hit on storage space. In reality, even if they were stored as encrypted binary/base64 in a nosql file system of structured data files, 4096 is pretty much the de-facto floor for disk space occupied by non-zero-byte individual files on most modern file systems.
...variable data size being a concern in cases where the transformed value is encrypted rather than hashed.