After market camera strap is, to put it bluntly crudely irresponsibly, a bad business decision. A strap is included with all newly purchased camera, so why would anyone want to spend additional hard earned cash on an after market ? Getting that extra battery or a memory card seems a wiser investment.
The only reason I could give is, a leather strap adds a touch of warmth to the otherwise a cold piece of equipment. Leather is the only reason, at least for me it is.
Cinema Camera and a strap, they don't go hand in hand. It's bad enough the camera is infested with cables of all type, we don't need another strap, be it leather or what not, to get in the way. You don't see a strapped camera on a gimbal, on a slider, or on a tripod, it's just a disaster waiting to happen. No serious amateur cinematographer would consider having a strap on, professionals would immediately dismiss the idea and flush it down the sewer.
So a camera strap has absolutely no place in an ever growing world of cinematography ?
In a gist, yes. Unless you're using a DJI Pocket or an action camera or a phone, one should always use a support of some sort to make videos.
However, there may be times when we had a camera on hand, and the surrounding was video perfect. You could of course use your phone to film the area, or you could make a motion picture with your hybrid camera mounted with that fantastic lens of yours. While the camera stablizer is incredibly good, it would be better if you could find a way to further stabilizing the camera.
And this is where a camera strap comes in handy. Instead of holding the camera with your hands, just hold the strap and let gravity ground the camera. If you have a long lens and it upsets the balance, simply rest the lens on your fingers. The clips won't be perfectly still, but the camera motion will at least be consistent and manageable.
I use the Sensuality strap for this type of shooting. It's more like a rope or a shoe lace than a camera strap, it may come in handy. Who knows.
