Or (as a wildlife photographer) why bother changing from a supertelephoto lens to a wide-angle lens and risk getting dust in the sensor when you carry a smartphone capable of taking good wide-angle photos anyway? Having something to get gopro-like footage without the bulk of a gopro could certainly be handy on occasion.
Yes. My 'normal' camera kit for a wildlife shoot is now my Nikon D850 + 200-500mm lens and my iPhone 12 Pro. The iPhone is great for capturing snaps of people, nice locations, etc, during the shoot although if I was doing a dedicated non-wildlife shoot I'd pack alt lenses for the D850.
I think the iPhone is actually better for capturing casual video and I use LumaFusion to give myself an on-phone video editing capability that is comparable with (say) Premier Elements. Again, if was shooting wildlife video I'd pack a tripod and a dedicated video head, but this is a massive weight commitment.
