There are a lot of preventative measures they could have taken, starting with just not leaving in dead code and paying attention to automated alerting. But the

There are a lot of preventative measures they could have taken, starting with just not leaving in dead code and paying attention to automated alerting. But the moral of the story is that they got away with it for so long that nobody cared about it anymore. After all, if it were truly a big deal why hadn't it broken years earlier. Then when the technical debt finally got called it bankrupted the entire firm in one go. Most of us (hopefully) have less devastating technical debt to deal with, but it is still a cautionary tale about what could happen if you ignore it for too long.