Well said. IMO, our history is not as clear to guarantee that a particular person had behaved /acted in a way which allow people to curse him / her. An authentic source for one sect is mere fabrication for the other. Only Allah knows what is true and whats not. In case, you curse a person for an act, which he/she had not done, then you will be accountable to Allah on day of judgement.
At the end, act of cursing will not make my meezan full of good deeds, which a person will require most on the day of judgement.