The interpolated (or not interpolated, in case of pixel shift or foveon) raw file(s) go through some rgb processing where the RGB working space is used. For example tone curves in exposure tool are processed in RGB working space as well as channel mixer, Shadows/Highlights, RGB Curves from Colour tab, Film Simulations (though this get a special processing because clut profile and working profile rarely match) and some other tools too.
After these steps the image is converted to CIELAB and the further processing is in CIELAB space almost up to the end of the pipeline (except you use the CIECAM02 tool, then of course additional conversions between CIELAB->CIECAM02->CIELAB have to be made), where it has to be converted to output profile again.