What you can't do, and what naive consumers of distributed systems often expect, is drive the probability arbitrarily low solely from the producer side. The con

What you can't do, and what naive consumers of distributed systems often expect, is drive the probability arbitrarily low solely from the producer side. The consumer has to be involved, even if they consider themselves to be a single-node process and don't want to bother with transactionality or idempotency keys.