I had addressed the wider point I thought, apologies if not clear enough. The mere existence of a failure, without other data, simply isn't good evidence for a

I had addressed the wider point I thought, apologies if not clear enough. The mere existence of a failure, without other data, simply isn't good evidence for anything you have claimed, and any assertion that "it's usually X" needs pretty serious support to be taken seriously. It's a complicated area, and reducing it too much leads to oversimplification at best.