My guess is ubiquity. That is, its no better than most watches technically. But bomb making is also about supply chains and training. When you make a detonator

My guess is ubiquity. That is, its no better than most watches technically. But bomb making is also about supply chains and training. When you make a detonator, you really, really want it to work. If you show someone "the wires go here and here" on a specific model you don't need to teach them "real" electronics, and theres less uncertainty that the final product will function. e.g. Arduino is rarely the best mcu for any given application, but it's popular because a) its easily to source and b) there are plenty of "recipes" to follow which don't require much expertise.