> it is hard not to see the power that comes from simplicity

Actually, it is quite hard for anyone who's not already versed in Lisp and equipped with some reasonable knowledge of basic FP constructs such as folds.

It's also important to look at the whole picture, and the author of the paper (and FP advocates in general) have this interesting tendency to completely ignore the opportunity cost of using FP and to dismiss the advantages of alternative approaches over FP.

Personally, I think laziness and immutability come at a very heavy price that explains why only the superficial aspects of FP (lambdas) have been adopted while the rest of FP remains the realm of research papers and conferences.