What is totally missing from a phone camera is the lens. Most point and shoot have some kind of zoom. I have a small camera and it has a 10x zoom, which is great at concerts etc. You can also set the exposure properly so for each shot, you don't have to try to get the phone to focus, then drag the exposure down since the iPhone will alway way over expose at a concert as it tries to average the light.
I don't ever use the iPhone for serious photos. For that I have a full frame Nikon and 4/3 Olympus with many lenses.
On trips where I don't want to take a camera bag, but still want decent photos, the small point and shoot with zoom lens allows me to take photos I could never take with an iPhone. If all you are doing is taking selfies then of course the phone is the way to go.
I think I can live with the smaller sensor on the iPhone X for the types of pics I take with the PaS but the lack of optical zoom may be a rare issue.
Does the OIS on both lenses on the iPhone X really make that big of a difference? I never use the 2nd lens on my 7 plus because the pics always come out a little blurry.