End-to-end exactly-once guarantees (except when used with Kafka as a sink today),

Hello,
Exploring these 2 systems to check how they can be complimentary. The messages sent by Kafka can be fed by Flink when we focus on that part of Flink’s capability. I understand Flink has other capabilities like ETL which are outside of Kafka’s scope.
Is there a view from the forum ?
Thanks

Flink, on the other hand, is a great fit for applications that are deployed in existing clusters and benefit from throughput, latency, event time semantics, savepoints and operational features, exactly-once guarantees for application state, end-to-end exactly-once guarantees (except when used with Kafka as a sink today), and batch processing.

The quote is above is from a blog by Neha Narkhede and Stephan Ewen here: Flink vs Kafka Streams - Comparing Features (confluent.io) (also found on data artisans blog.