I don’t know why people keep parroting that crap. PHONES CAN HAVE REPLACEABLE BATTERIES AND STILL BE FULLY WATERPROOF.
I had a galaxy S5, it had an SD card slot, replaceable battery, headphone jack… AND WATERPROOF.
It was also thinner than my current OnePlus with the camera bump.
There is overhead but Vulkan allows you to batch draw calls in a far more efficient manner. It can also generally use multi threading to feed a GPU even if the game isn’t coded with that in mind. Basically Vulkan offers so many improvements to efficiency and parallelization that the overhead is a drop in the bucket compared to the overall speedup in draw call optimization alone.
It is insanely disingenuous to think that manufacturing capabilities that could cheaply mass produce waterproof cameras and consumer electronics for 30+ years couldn’t handle miniaturization.
On that note, I never once had water ingress issues with my S5 in a few years of ownership, and I would shower and swim with it. Just had to make sure the back was all the way on for the gasket to seal (the phone would detect it and warn you)