Well it's not pointless. The term as used in FP has a pretty well-defined meaning [1] and it is a quality only some programs have. And a program having that qua

Well it's not pointless. The term as used in FP has a pretty well-defined meaning [1] and it is a quality only some programs have. And a program having that quality enhances (fast-and-loose) equational reasoning. [1] I can point at most Java code and prove how it fails the definition. It's not especially hand-wavey.