I've never really thought about it quite this way before, but: pure functional systems basically want to ignore time. In some contexts this is ok or even desirable, but in other contexts it is counterproductive and futile.

Time is pretty critical to physical reality, one way or another, and the closer you get to it with lower and lower-level language systems, the harder it is to ignore.

It seems to me there needs to be some very basic computational/mathematical theory that integrates time more fundamentally into language/instructional design without being procedural per se. There probably is one but I don't know what it is, or am not recognizing it for what it is.

I like how Paul Chiusano answered the main question:

    "If Haskell (or XYZ) is so great, why hasn’t it taken over?"
    "The simplest explanation is probably that Haskell is not that much better than, say, Java,"
    "for many of the software systems people write today."

The most involved part of a CRUD app is writing data and checks around it. This "checking" part can be written with little interaction to the outside world.