I'm at a loss for your criticism.

Didn't the original post say, "How they [hashes] get implemented in solving this problem is the question"?

Merkle trees implement cryptographic hashes.

>Git chain hashes.

Git chains hashes? Yes, of course, along with diffs.

How the permanent web will implement digests in various applications is the question. Whatever the answer is for link rot, the guaranteed solution will implement and depend upon cryptographic hashing algorithms. There are already many examples of this class of problem being solved by utilizing hashes.

You may be trying to read too much into my statement.

It's simply that hashes, alone, do little, and that hash-free solutions might well exist as well.

Bald assertions of simple necessary and sufficient solutions are almost always mistaken.