Any left-handed photographer here to help explain the rationale behind this product?
I will admit I chuckled when I initially read this thread, for the reasons stated above - the shutter button is on the right, the camera is designed to be held in the right hand, so why would even a left-handed photographer need this?
I am a right-handed photographer, and I can tell you why I will likely get one of these left-handed straps.
I was out shooting in earnest for the first time a couple of days ago with my 1D X and my new EF 600mm f/4L
IS II. I have the RRS replacement foot on it, for an Arca-Swiss connection to my gimbal and monopod, but also to connect the Kirk 1" clamp on the end of my BR RS-4 strap. However, when using a lens that large, you need to support the weight by the tripod foot while shooting handheld, and ideally lift the camera to your eye by the tripod foot as well, rather than by the camera body (which would place all of that weight on the lens mount - there's a reason Canon puts strap lugs on the lens barrel!). So, when carrying a supertele on the Blackrapid, IMO it's best to have it hanging on the left
side of your body, so you can use your left hand to raise it to your eye by the tripod foot and support it while shooting with your right hand.