True. But knowing why something happens would allow engineers prevent such mistakes in the future. I know that consumer only should care about the finished product, but it's important for them to understand that even most scrupulous QA and testing can't catch everything.

Here is the problem: let's assume that some fraction of semiconducting elements inside the phone were made from a faulty silicon crystal. Because it has some mechanical impurity it offers an increased resistance but the phone performs OK and passes checks. Unaccounted for this flaw heat disperses into the battery and you get an explosion. That's a sound theory, but even simulating it on a computer would require quite a lot of work to pin-point the most likely components to carry the fault. And this designer should put his inquisitive prowess to landing people on Mars rather than doing smartphone QA.

Just in case, I don't defend people who made this mistake. That's a terrible issue, fact that it's of unknown cause and depends purely on chance for what we know is even worse. But if a boob like me can think off of five or six possible hypotheses (and even more for kale)… imagine how many possibilities and explanations could make an engineer who actually knows this stuff. Finding a reason for any of these consumer product faults would basically need a research team. I can only hope that a proposal titled "Let's find a way to avoid exploding phones to avoid lawsuits, bad PR and harming our clients" would not have many problems with getting a budget.