Ok, I understand your point and no I don't think this was some sort of false flag. But still the question remains who benefits from this trajedy, regardless of who fired the rocket.
I imagine it will be something as mundane as a combination of:
1. Sophisticated weapons in the hands of people with limited training
2. Poor or no rules of engagement
3. Poor or no target verification
4. Poor or no command approval required for engagement
5. Education, alcohol, bravado, and hubris...