The narrative in Why Functional Programming Matters (“WhyFP”) is that it is not enough to simply remove features, but to take advantage of their removal to add other, more powerful features.

The paper gives laziness as an example. It’s made possible by idempotency. Which is made possible by the removal (or careful management) of side-effects. Which then allows certain otherwise impossible ways to express infinite data structures.

http://www.cse.chalmers.se/~rjmh/Papers/whyfp.html