Blame isn't like a dinner bill, where if one person pays in full there is nothing left to pay, because more than one party can, at times, completely change the outcome. In this case, yes, Hamas bears full responsibility. But Israel also bears a great deal of responsibility unless it was impossible for them to make different choices. If Israel is such a mindless actor as to be triggerable in every detail by Hamas to brutalize the Gazan population, then the Israeli government is functionally an arm of Hamas' terror organization and needs to be dismantled along with Hamas. However, I rather think this is not the case, and therefore Israel also bears responsibility for specific choices it is making in how to respond.