In general, people (and societies) often believe that if you know about something bad, you have a duty to stop it. If you don't know about something, then obviously you can't be blamed for not stopping it.

I don't think that's very obvious. We often transfer responsibility to certain roles. The president of a country is supposed to be responsible for what the bureaucrats under him are doing whether or not he knows what they are doing.

In general it's a useful social norm to hold people accountable for the promises they make whether or not they can tell you a story of how they didn't have proper information to fulfill on the promise.