> makes it easier for integrators to build a robust integration with you

No, don't say 'easier'. It makes it possible to build a robust integration. We need to stop with this notion that omiting idempotency from an API just makes things "more difficult" to develop. Without idempotency, you garuantee that the resulting system is "difficult" to use and full of nasty issues that are waiting for the right conditions to collapse the entire house of cards you've built.

So many SaaS providers have never even heard of idempotency, let alone design it into their APIs. Many people believe you can just sprinkle it on as a library without having to think about it.

All APIs with multiple distributed servers must support idempotency. Refuse to do business with any organisations who do not design this into their APIs!