I think you’re glossing over “radically divorced from their original purposes” here. The point is not that photographs are inherently surreal—clearly, the opposite is true. It’s that photos are uniquely suited for surrealist manipulation, more so than any other representational art. A painting, for example, even a photorealistic one, is a step further removed from reality, or more, depending on the artist’s style. But a simple photograph captures what’s real in a way that other art doesn’t.

It’s the juxtaposition of a work with another that makes it surreal, not necessarily the work itself. Think about editing a photograph of Neville Chamberlain and replacing his head with a jellyfish. Neither photo is in itself surreal, but by combining them you have made surrealist political commentary.

I'm not sure this is the right sub for this question but you seem to be ignoring the specifics of the claim?

But the Surrealist understanding of photography turned on more than the medium’s facility in fabricating uncanny images. Just as important was another discovery: even the most prosaic photograph, filtered through the prism of Surrealist sensibility, might easily be dislodged from its usual context and irreverently assigned a new role. Anthropological photographs, ordinary snapshots, movie stills, medical and police photographs—all of these appeared in Surrealist journals like La Révolution Surréaliste and Minotaure, radically divorced from their original purposes.

It's not making a statement about all photography ever. It's making a statement about why photography was of interest to surrealists. Juxtaposing images is an action, not something inherent to the images being juxtaposed.

Have you looked at any surrealist photography? It might help you make sense of what is meant by "the irrational juxtaposition of images".