I think aurelien addressed in the past. Filmic is for technical contrast, you do the tone mapping and maybe some contrast is lost in the midtones while doing so, hence why the contrast slider exists in filmic. It is not meant for creative adjustments of contrast. You get it to a good starting point and then use expose or tone equaliser for artistic adjustments.
Here is the explanation: Which module for contrast to use? Filmic or color balance rgb? - #10 by aurelienpierre