True. But given that the difference in implementation appears to be arbitrary, the real differene between oop and fp must be evaluated in the domain of empirical research regarding their ergonomics. If one matches your natural thoughtpatterns more closely (be that abstract or concrete modelling) or educative efforts (it might be that one is easier to understand), or ease of implementation, that would be an argument for or against it.
Although Java might be conceptually weak, empirically speaking it's a big winner, because developers appear to value ease of education, connectedness with others, availability of jobs and job security more than feeling stupid for not understanding lambda calculus. (that doesn't render formalist approaches invalid)
You absolutely do not need to understand lambda calculus to leverage FP. (And similarly, you don’t need to understand Turing machines to leverage imperative styles.)
Tools like ReactJS and regular expressions would indicate that the market for FP is quite large in spite of the popularity of Java as well, IMO
Although Java might be conceptually weak, empirically speaking it's a big winner, because developers appear to value ease of education, connectedness with others, availability of jobs and job security more than feeling stupid for not understanding lambda calculus. (that doesn't render formalist approaches invalid)