I am the author of the post.

I think in cases where you are running totally different computations in different systems the Lambda architecture may make a lot of sense.

However one assumption you may be making is that the stream processing system must be limited to non-blocking, in-memory computations like sketches. A common pattern for people using Samza is actually to accumulate a large window of data and then rank using a complex brute force algorithm that may take 5 mins or so to produce results.

One of the points I was hoping to make is that many of the limitations people think stream processing systems must have (e.g. can never block, can't process large windows of data, can't manage lots of state) have nothing to do with the stream processing model and are just weaknesses of the frameworks they have used.