It’s the same story as the Casio F-91W as well as the AK-47. Terrorists (or just any armed paramilitary group) who live in the back country far from common supply lines have a great need for standardized, rugged, reliable, and repairable technology. By living that life, they’re basically forced to think about these issues as a matter of survival.
Well I think the F-91 is durable, it’s probably not repaired as much as discarded as it is cheap. Disposable is likely the advantage there.