And phones don’t indeed replace many other devices. Like camaras too, for example. If you want to do really good photography, you actually need different kinds of lenses. Although lenses exist for smartphones, they are not that widespread, and using a camara is therefore still important.
Also a big point is the ergonomics of it. Handling a camara is much easier for long and complex photography sessions. Same with having a calculator at hand. It’s easier to punch numbers in a physical keyboard. Or to handle a flashlight, or using a real keyboard to write a document. The list goes on and on and on.