Rashi, Rambam, the Maharal, the Rosh, the Rema, etc. are all usually referred to by their acronyms. This custom makes sense in a culture that is mostly transmitted through the written word where ink ...
Rabbi Yitzchok Alfasi was known as the Rif. The Roshei Teivos of his name is רי"א, and as far as I know there is no other historic figure known as the רי"א. Then why was he known as the Rif?