Looking at 7574 and Bittorrent's BEP 30, unless I'm missing something, the only part that is resisting the attack mentioned in the source article and what you a

Looking at 7574 and Bittorrent's BEP 30, unless I'm missing something, the only part that is resisting the attack mentioned in the source article and what you are replying to, comes from also specifying the total length of the data hashed, along with the block size. So you're getting the root hash, total size, and leaf block sizes - it's that secondary information that is necessary to prevent the imaging attacks mentioned in the source article and what you are replying to. With a better construction (Sakura, ...), that total and block size information are unnecessary. I wonder if any almost-compliant RFC 7574 or BEP 30 tools accidentally ignore those other sizes.