> Why don't we use what the metal uses, instead of these "expressive abstractions"?Because the "expressive abstractions" are much easier to reason about and save programmers lots of mental effort. And, as I have commented upthread, ifs and for loops are by no means the only such abstractions.
> because the latter is unfamiliar, it's spoken about in the same manner you present: as if it is some highly abstract, complicating, high-level feature
If expressing your program in the lambda calculus is easy for you to reason about and saves you enough mental effort, go for it. But don't expect your code to be readable or understandable by many other people. The reason why ifs and for loops (and other "expressive abstractions", since as I have said, those are by no means the only ones) are ubiquitous in programs is that they are easy for lots of programmers to reason about. Whereas the lambda calculus is only easy for a very small subset of programmers to reason about.
