Here's why:
* The Baudelaires' parents died in a fire. Their deaths are described as a tragic accident in the first book, "The Bad Beginning."
* Count Olaf's death is not explicitly shown in the series. While he is repeatedly thwarted by the Baudelaire children and faces many dangerous situations, he is never killed by them.
* The series focuses on the Baudelaires' struggles against Count Olaf. The focus is on their survival and their attempts to uncover the truth about their parents' deaths and a hidden fortune.
The idea of the Baudelaires' parents using poisonous darts to kill Count Olaf is not a part of the original series.