The objection I have to this paper is that I keep seeing SQL forced onto streaming workflows when the functional programming operations provided by the non-SQL

The objection I have to this paper is that I keep seeing SQL forced onto streaming workflows when the functional programming operations provided by the non-SQL APIs of systems like Flink and Spark are a lot easier to think about in this context: SQL stream joins often have very surprising performance properties and it can take a long time to figure out the tunables needed to make them perform at scale.