You can not deny that, if Hamas actually had a problem with it, then they should surrender everyone who killed innocents.

Yeah they probably don't have a problem with it, that's true enough and can't be defended. But they didn't go "we should go there and kill civilians", is what I mean. Some people have that impression about the attack and that's playing right into Israel's hands. Unfortunately punishing soldiers who commit warcrimes is a standard neither side is trying to reach.

Also, from what we know the music festival wasn't a one-sided Hamas massacre; there was combat with the IDF and many of the people who died died in the crossfire. Not saying there weren't people who killed innocents (particularly the guy who threw that one grenade should be hanged), but the image that Hamas went in guns blazing and killed a bunch of people is at this point in time plain Israeli propaganda that spread before the details were known.