> Like are there other people claiming that this purist version of exactly-once does exist?
In my experience, the purist version of "exactly-once" exists as a vague, wishy-washy mental model in the brains of developers who have never thought hard about this stuff[0]. Like, once you sketch out why idempotency is important and how to do it, folks seem to pick up on it pretty quickly, but not everyone has trained their intuition to where they automatically notice these sorts of failure modes.
[0] I don't mean this as a slight against those developers--the issues that arise from distributed systems are both myriad and subtle, and if you've spent your time learning how to make beautiful web pages or cool video games or efficient embedded systems, it seems reasonable to not know anything about the accursed problems of hypothetical Byzantine Generals. Or maybe you're fresh out of a bootcamp or an undergraduate program and haven't yet been trained to expect computers to always and constantly fail in every possible way.
In my experience, the purist version of "exactly-once" exists as a vague, wishy-washy mental model in the brains of developers who have never thought hard about this stuff[0]. Like, once you sketch out why idempotency is important and how to do it, folks seem to pick up on it pretty quickly, but not everyone has trained their intuition to where they automatically notice these sorts of failure modes.
[0] I don't mean this as a slight against those developers--the issues that arise from distributed systems are both myriad and subtle, and if you've spent your time learning how to make beautiful web pages or cool video games or efficient embedded systems, it seems reasonable to not know anything about the accursed problems of hypothetical Byzantine Generals. Or maybe you're fresh out of a bootcamp or an undergraduate program and haven't yet been trained to expect computers to always and constantly fail in every possible way.