Fine, but that doesn't address the point GP is making. This is a subject near and dear to my heart, since I am constantly frustrated by the opaque nature of functional programming tutorials on the internet. Functional composition is very difficult for beginners to pick up, and using single letter variable names for everything significantly compounds that problem. There are many concepts in FP that can elevate the craft of software design, and it's a tragedy that a lack of approachable instructional materials convinces most programmers that either they are not smart enough to learn it, or that it's Ivory tower nonsense. Ease of readability is a virtue in any programming environment, and I personally feel that the FP community as a whole should make lowering the barriers to entry a top priority. I'm grateful to all of the people working hard to bring functional programming to the masses, but I have a sneaking suspicion that many functional programming practitioners like that it looks complex and difficult to outsiders. Just my two cents.
Because the syntax favours terseness for readabilities sake (to see structure and patterns rather than reading a description of the variable).
Because Python specifically favours verboseness and has many principles around using long names, underscores instead of camelcase and the like.