I came here to note the same thing, from an aerospace perspective. In a formal development following something like ARP4754A even before one works on the requi

I came here to note the same thing, from an aerospace perspective. In a formal development following something like ARP4754A even before one works on the requirements that a system has to meet, the high level system functions are considered and a Functional Hazard Assessment is done to look at the criticality of those functions failing. Then one can add requirements and architectural mitigations as the system and Safety Assessment is developed.