"The key property from my PoV is that with this method, no secrets are required to sign log records. And if there is no secret, an attacker can obviously not take advantage of the secret to hide his tracks. So this method actually provides a very good integrity proof and does not create a false sense of security.
This removed a major obstacle that always made me not like to implement log signatures".
Read the the rest of the reasons from Rainer Gerhard’s blog.