Re: In their defense (sic)
And I'dd add to that the obvious fact that the cargo hold is packed with other flammable material, like, hundreds of other laptops with their Li cells veery close to one another.
The nice thing about Lithium cells is that they include everything they need to burn at high temperatures, which means you can't easily distinguish the fire they produce (water doesn't extinguish the fire, it may only help to cool down the surroundings and prevent other stuff from catching fire). So if there is one cellphone or laptop on fire, it's bad enough, but with good training or thinking, you can make your plane survive. Not with tens or hundreds of these things burning simultaneously in one cramped area.