why can't you blame the recent attacks on refugees??
Because the people that committed the attacks could have done so without being accepted into Germany as refugees. A lot of recent attacks were also committed by EU nationals.
You can't say that allowing refugees in caused the attacks without being able to say that without letting them in there would have been no attacks on German soil. If anything the actions of the German government probably saved more lives on both sides than if they'd let the whole thing go to ****.