I believe that you hit the point! If you look, I give as examples Spring or Angular. For example, if you compare React versions usage, versus Angular versions usage, you will realize that Angular code is harder to maintain up-to-date. Please. note that I am not an Angular detractor, I even was a contributor in the past, but I have accepted the numbers and how its creator (Misko Hevery) has created a new framework closer to React philosophy.

And of course, OO is amazing. Its best modeling the reality, it is a 1 to 1. As you comment about Alan Kay, which I feel that Smalltalk is one of the greater OO languages, and it was so good, that most of the modern ways of working emerged from them.

But I worry that several programmers forget about that, may be they do not understand what is behind, or may be have hard time to create maintanable code.

I think that the problem that they face origins in the state isolated inside objects. The same good thing, which is hidding information, also cause lots of problems. I do not know if it specific for other languages than Smalltalk, but what I found is that once programmers have created an object with an state,

later they need its state other places, and then, or they start creating strange couplings, or they start duplicating data. That makes programs harder to maintain. But FP, often have one source of truth, and the results are transformations of that source. My concern about FP is that source often is "public", but for now, it seems that it manages better some problems.

I do not know which is the right answer, but for example, in CS courses (at least in my country), they focus mainly in OO, and they almost neglet FP to a couple of courses. I even was teacher in one fo these degrees that they had zero subjects about FP, so I manage to introduce it a little.