Bear with me, but raising kids taught me a lot about this kind of things.
Even at two or three years old, I could say things to my children that relied on them understanding sequence, selection, and iteration - the fundamentals of imperative programming. This early understanding of these basic concepts why you can teach simple imperative programming to children in grade school.
This puts the more advanced techniques (CPS, FP, etc.) at a disadvantage. For a programmer graduating college and entering the workforce, they've had life time of understanding and working with sequencing, etc. and comparatively very little exposure to the more advanced techniques.
This is not to say it's not possible to learn and become skillful with these techniques, just that it's later in life, slower to arrive, and for many, mastery doesn't get there at all.
In my experience, when you ask people to tell you what "basic" operations they do for e.g. multi-digit number additions or multiplications, you get many different answers, and it is not obvious that one is better than another. I don't see why it would be different for languages, and any attempt to prove something would have a high bar to pass.
I'm not arguing that one language is _better_ than another... just that people are exposed to some programming concepts sooner than others. That gives these ideas an incumbency advantage that can be hard to overcome.
> any attempt to prove something would have a high bar to pass.
Honestly, the best way to (dis)prove what I'm saying would be to put together a counterexample and get the ideas in broader use. That would get FP in the hands of more people that could really use it.
This alludes to my biggest frustration with FP... it solves problems and should be more widely used. But by the time people are exposed to it, they've been doing imperative programming since grade school. It's harder for FP to be successful developing critical mass in that setting.
At least, this is my theory of the case. I'd love counter examples or suggestions to make the situation better.