The difference is training. Scores of operators on the ground are already trained and experienced on the Stinger platform and the development of complete already.

Backfilling a proven stock item is faster than infilling a new platform. Refer to the training cycles required for tanks provided by the UK. Those tanks have qualified operators ( with matching tactical-operational skills, but there are few personnel to back up their abilities. The Stinger is valuable because of the established user base compared to that.