Cambridge Dictionary gives this definition and example about "be responsible for sb/sth"
to have control and authority over someone or something and the duty to take care of them
He is responsible for the council's waste management department
and this one about "hold sb/sth responsible"
to blame someone or something for something bad that happened
He was held responsible for the accident.
I guess I understand part of those. I see the difference.
First example indicates he is actually responsible for ...
second example means he is not necessarily actually responsible for ... Maybe, he should not be responsible for the accident.
Speaking of "should not", the following expressions seem to mean the same thing.
He should not be held responsible for the accident.
He should not be responsible for the accident.
I guess both of them indicate that people should not accuse him because of that accident. I really don't see the difference with addition of "should not".
Google Ngram shows that "should not be held responsible" is more commonly used than "should not be responsible". However, that graph does not seems helpful.
Am I missing something? Could someone please give a hint? Thanks in advance.