Only the cheapest of cheap mech boards (or vintage boards with no adapter) will be completely unable to be re-mapped, but the closed-source firmwares and their apps are generally quite limited and unpleasant to use. Not the biggest deal in the world if you use a full size or "tenkey-less" that simply lops off the numpad, but it gets more and more important the smaller you go. Even the very popular "75%" keyboards can benefit from good software as people get strong opinions about what they want the right-hand column to do.