No, these APIs are intentionally designed to be equivalent to hashing all data at once - i.e. to make it possible to hash in O(1) space.

There's nothing "disfunctional" about that.

"Incremental hash function" has a very different meaning and doesn't seem to have any relevance to what is discussed here: https://people.eecs.berkeley.edu/~daw/papers/inchash-cs06.pd...