question here is "why does a photograph exist". Problem with this kind of question is that the answer is either personal and subjective, or it's an enumeration and an attempt to unite all (or subset) of the subjective reasons into some coherent theory.
What You're referring to reminds me of something like event photography. Photos that serve as a souvenir of an event / person / thing. Pictures that can be described as having "moment captured in time" as their raison d'etre. These are indeed unlikely to be replaced anytime soon.
But that's only a small subset of what we use photographs for. Lots of photography is about capturing an emmotion, rather than reality. Think of all the marketing (to name the biggest economic factor). If You're making an ad for watches, You don't give a damn if that cool guy wearing them is real or not. If You're a hotel or some travel agency, You are probably going to need "smiling happy couples / families around an infinity pool with a sunny beach as a background". Oh, hej, looks like that's actually a Stable Diffusion prompt...
What You're referring to reminds me of something like event photography. Photos that serve as a souvenir of an event / person / thing. Pictures that can be described as having "moment captured in time" as their raison d'etre. These are indeed unlikely to be replaced anytime soon.
But that's only a small subset of what we use photographs for. Lots of photography is about capturing an emmotion, rather than reality. Think of all the marketing (to name the biggest economic factor). If You're making an ad for watches, You don't give a damn if that cool guy wearing them is real or not. If You're a hotel or some travel agency, You are probably going to need "smiling happy couples / families around an infinity pool with a sunny beach as a background". Oh, hej, looks like that's actually a Stable Diffusion prompt...