When you approach the world committed to the theory that all bad things are caused by the powerful oppressing the weak the facts become unnecessary. You already know who is responsible for the violence--the powerful. You can always explain away any violence by the people you caste as the weak as the result, ultimately, of the actions of the powerful. That is why the Palestinians are never held to account for terror--it is not really thier fault. The arguments about what Arafat knew and how much control he or some other part of the Palestinian leadership has or which side committed what act first are ultimately irrelevant. The theory through which reality is interpreted imposes a structure on perception. More Palestinian violence is only more proof of what the Israelis are doing to them. It is becasue they have defined as the weaker party that nothing they will ever do will ever be more than another reason for more Isreali consessions.
The fact that Palestinian terrorism is not necessarily centrally directed or coordinated is not proof that it is caused by oppression. There was plenty of spontaneous violence on the part of whites against blacks in the South. It never caused anyone to ask what the blacks were doing to those poor white people to make white people hate them so much.
The real victory in the war for world opinion was won when the conflict was recast as the Palestinian-Isreali conflict. That is what made the Israelis the strong and the Palestinians the weak. When it was the Isrealis against 200 million Arabs (who are, incidentally, still at war with the Israelis) the Arabs were still to some degree held to some kind of account for thier actions.