Where we saw friction with Flink was mainly: 1.) Operational overhead (jobs, state backends, checkpointing) 2.) Generic sinks not being optimized for ClickHouse (batching, small inserts, etc.)
We focused on making scaling a property of the pipeline itself (just add replicas) and optimizing specifically for ClickHouse ingestion patterns.
So Flink is more general, this is more opinionated and focused on this specific use case.