[throwawaydbfif]

Erlang and common lisp have been around for a long time, and functional programming is nothing new. The reality is that most business problems map conceptually to communication between objects, and that IDE's which greatly help developer productivity work a lot better with objects.

Functional programming has origins in lambda calculus and academia because mathematical problems map more easily from pure math to functional programming. It's really popular in the circles where it's more useful/easier than OO.

Honestly I don't think the people 20 years ago chose OO for most business languages over functional out of ignorance. They had a choice and decided that OO was better for business problem solving languages like Java even though a large majority of programmers from that era were math majors and familiar with functional syntax.

I feel like we're in one of those cycles where a large number of a previous generation have retired and it's time to learn some of these lessons all over again.

Notice how many wood commercial buildings have been going up in the last 15-20 years? A lot, and just long enough after everyone involved in all the great city fires of WW2 to be too dead to object.

[fmap]

Who "choose" OO 20 years ago and (much more importantly) why?

I'm going to ignore the social component... that said, we work in a wonderful profession where the world is changing completely every decade and many design decisions from the previous generation make no sense anymore. The business case for developing your application in COBOL rather than Common Lisp may have been sound 20 years ago, but today many of the reason why you didn't choose lisp are invalid (e.g., garbage collection takes milliseconds rather than seconds).

Note that this is not the case in more mature fields such as construction.