bhe, The Arizal had nothing to do with nusach sefard. He established the sefaradi nusach, also known as ???? ???? ?????. That is what people from North Africa, Syria, Persia etc. use.
The Nusach sefard that chasidim use, is essentially nusach ashkenaz, but incorporates the tikunim of the Arizal and the other mekubalim, and was established by the talmidei Baal Shem Tov, from the Baal HaTanya/Alter Rebbe (hence Nusach Ari) and onwards.
The sense it makes , is that you can go to a mesora that goes back further, because even if your father davens sefard, his great great grandfather from 300 years ago, davened Ashkenaz (because there was no sefard then).