The term "spiral" has a more narrow definition in a mathematical context, as a curve which lies in a single plane and moves towards or away from a central point, with a continuously changing radius. The mathematical term for the 3-dimensional curve traced where the locus progresses at a fixed radius from a fixed line while moving in a circular motion around it is a "helix". Since the very purpose of a stairway is to change elevation, it is inherently a 3-dimensional path.
Loose everyday usage conflates the terms helical and spiral, but the vast majority of circular stairs are actually helical.[13][14] True spiral staircases would be nonfunctional flat structures, although functional hybrid helical spiral staircases can be constructed. This article attempts to preferentially use the terms "helix" and "helical" to describe circular stairways more clearly and precisely, while reserving the term "spiral" for a curve restricted to a flat plane.
Absurd! This is mostly not useful and non informative! This is just someone's nitpick with citations! I have mathematicians on wikipedia! They're bad at using this site!