If there is no such thing as exactly-once delivery because the recipient might not feel like deduplicating, then there can be no such thing as at-least-once del

If there is no such thing as exactly-once delivery because the recipient might not feel like deduplicating, then there can be no such thing as at-least-once delivery either, because the recipient might not feel like being endlessly available for delivery either. Or the mailman might not feel like (re-)attempting deliveries endlessly either. Or the sender might not feel like re-sending things endlessly either. Is this insightful? Surprising? What's the point of the debate?