Merkle Tree Certificates basically uses the same structure as Certificate Transparency today. Merkle Ladder uses a weird variation claimed to be useful to DNSSEC. I think it's rather just to seem novel ( https://datatracker.ietf.org/ipr/search/?submit=draft&id=dra... )
I found buzzwords for this; Quantum-Resistant Decentralized PKI / DNS:
Multilinear/Hash-based VCs and Sum-Check protocol for Stateless PKI (with Sparse Merkle Tree (SMT))
PKI-over-Log with Hyper-Trees, Decentralized PKI (DPKI), XMSS^MT, M-FORS and F-SPHINCS+ (stateless),
"Spartan: Efficient and General-purpose zkSNARKs without Trusted Setup" (2020) https://link.springer.com/chapter/10.1007/978-3-030-56877-1_... :
- Spartan implements the Sum-Check protocol with Multilinear Polynomial Commitments, which is hash-based like XMSS and SPHINCS+ (unlike Verkle trees which are built on KZG which relies on the "Discrete Logarithm Problem" (which Shor’s broke)).