Why Isn't Functional Programming the Norm? [video]

I didn't listen to the video, but the title raises questions. What is functional programming? Nowadays, most languages are multi-paradigm, it's not so clear what is functional programming (or a functional programming language).

For instance, it's very common to have data types with mutable state in OCaml, or to use non-mutable data-structures, closures, higher-order functions in let say Python. I don't see such a clear dichotomy between functional/non-functional programming languages anymore.

Besides, there are other language "features" that I feel have more impact on the code I write. For instance, static/dynamic typing, asynchronous I/O vs actors vs threads, module systems.

I see functional programming more as a tool and a programming discipline, well-suited to solve some problems, rather than a paradigm that one should adhere no matter what.

The talk actually takes time to answer these questions.

The title is also a bit clickbaity because the talk acknowledges that fp as a style is becoming common.