Mono Compatibility

I mix in stereo. I have a single Bluetooth speaker I connect to my phone to listen to mixes I've sent to my phone for a 'modern world' mono comparison environment, if you will. I use LCR mixing technique. Playback invariably reveals less of the right side than the left, which makes sense in a L is mono world. Many say LCR is the way mixing should be done, of course with all the inherent subjective ness implied. My question is, 'why mix anything to R exclusively if all you get from it is the stereo verb from the left side'?