It can get way harder when your initial design made incorrect assumptions about the delivery semantics you were using, so you didn't know you'd need it.
Edit for example:
Someone could have a low-latency problem that seems like it could be a fit for a streaming application. They could look at docs and see "ooh, with Flink I can do exactly-once writes to Kafka" in one place, and choose to use that. But if they don't dig deeply into what that means, they may miss the latency impacts of having to checkpoint every time to commit a set of writes to Kafka. And by the time they figure this out, managing both "low latency" and "exactly once" in the code they wrote might be a really hairy problem.
It can get way harder when your initial design made incorrect assumptions about the delivery semantics you were using, so you didn't know you'd need it.
Edit for example:
Someone could have a low-latency problem that seems like it could be a fit for a streaming application. They could look at docs and see "ooh, with Flink I can do exactly-once writes to Kafka" in one place, and choose to use that. But if they don't dig deeply into what that means, they may miss the latency impacts of having to checkpoint every time to commit a set of writes to Kafka. And by the time they figure this out, managing both "low latency" and "exactly once" in the code they wrote might be a really hairy problem.