Because what I concentrate on is the video evidence and yes, the physical evidence presented at the scene, while others prefer to speculate on the inner processes of people they are lucky enough never to have to meet in person.
And once again you are forgetting that Assad has a chain of command made up of people, including loose cannons like his brother. And that he and his family were encircled on the day of the attacks. And that Jobar puts his own sorry carcass in the line of fire for mortars and rockets.