I didn't say that MD5 would solve the configuration problems, but that the fact that just mis-configuration errors can cause lots of damage should clue people into the fact that the protocol has vulnerabilities to deliberate attack.
Every protocol is vulnerable if the principals are mis-configured (i.e. do not follow the protocol). The protocol for crossing a busy street at the light involves checking for the green light before crossing the street. A mis-configured principal checks the light, ignores red or yellow, and immediately crosses. Does it mean that the protocol is broken or does it mean that a principal is broken? Alex P.S. In this specific case I am strictly looking at "misconfiguration causes problems" implies brokenness of the protocol.