Lots of low-value names required. Those names will inevitably either be badly chosen or have taken far more time to make up than they are worth. That's assuming the code isn't written by that one guy on every team who stubbornly insists on

   var x = three();
   x = two(x);
   one(x):

(having the names certainly is nice to have in the debugger, but I'd rather have those intermediate results be an explicit debugger feature than junk taking up mental bandwidth all over the code, at all times)

Good point and yours does look better :)

The beauty of not using variables is that they don't pollute scope: a promise to the reader that it's perfectly fine to forget about that inermeditate result immediately after seeing it passed into the next step of the pipeline. Otherwise, you never know if it will perhaps show up later for some unexpected purpose. In a left-to-right language, those values that do get a name implicitly stand out