Conceptually, one of the challenges of streams as first class citizens is that humans don't do well with them. For the purposes of analysis, humans need a "snapshot" or fix on the data. This way they can derive insights from the data and act on human things. The reality is that, for many real-world scenarios, a real-time view of the data is not just a luxury, it's actually a drawback, because data changes are noisy. Many human problems deal with abstract representations of the actual data, and so imprecision is part of the problem.

I really like the talk from the point of view of simplifying the system-wide problems caused by a gigantic mutable state. But I feel that at the border of system to humans there will be other issues to discuss.