It conveys a false sense of correctness. Usually the system doing the processing has to use higher level or external methods of providing idempotency.
For example TCP implements "exactly once processing" by your definition but you probably still want Stripe to include idempotency keys in their charge API so you don't pay twice.
For example TCP implements "exactly once processing" by your definition but you probably still want Stripe to include idempotency keys in their charge API so you don't pay twice.