The author of Holism and Evolution, Jan Smuts, used the Greek word "holos" as the root of "holism" instead of "whole" (the book was English, and "whole" was commonplace). In later years, wholistic was coined, but never caught on. While there could be other reasons for the choice than making it sound more scientific, it sure seems to be the case.

This is one of those examples of the English language that annoys me.

https://www.etymonline.com/word/holistic

https://en.m.wikipedia.org/wiki/Holism