The easy answer is: "Because it is a statutory requirement". An Alarm Philosophy has to follow specific standards, and in a court of law you could be held accountable for not applying the standards to your alarm system design. However, there is more than the legal aspect to it. The Alarm Philosophy exists for operational, safety, work environmental, design and behaviour reasons - and ultimately, cost effectiveness.
There are many factors to consider when analysing why some alarm improvement projects fail. For instance, some companies underestimate the time and people needed in order to have a successful project. What actions can you take in order to ensure success?
It is easy to understand that the consequence of not responding to a critical alarm may be incidents, accidents and potentially enormous costs. However, it is not that straight forward to understand that there is a cost associated with any alarm. How can we quantify that cost?