Some houses (like mine) are concrete block though too.
Even still though, fire will work on the other parts, and that is really the biggest threat for my own home defense. Simply put, so far, my only counter to it is to try and keep folks too far away to throw it, but it's a difficult tactic to fight.
Of course, any band doing so, is pretty much going to burn up the resources they are after, so shouldn't be a likely tactic, but still, I really worry about this one.. I think I'm adding a sprinkler system to my list. In FL, we get lots of rain, so don't normally need it, but may be a good idea.