That page includes an example that shows PHP's incremental hashing is what you describe as "dysfunctional". It hashes "The quick brown fox jumped over the lazy dog." in 1 part, and in 2 parts, and shows that the resulting hashes are equal.

For anyone curious PHP ultimately uses this definition in their introduction portion of the hash extension:

> This extension provides functions that can be used for direct or incremental processing of arbitrary length messages using a variety of hashing algorithms, including the generation of HMAC values and key derivations including HKDF and PBKDF2.