For many years, 35mm SLRs were the mainstay of “general” photographers. Medium- and large-format offered better image quality through their larger film sizes, and held sway among fine-art, architectural, landscape and even wedding/portrait photographers for that reason (and, in the case of large-format and studio still-life, for the cameras’ perspective-correcting movements). But, by far, the most camera sales were 35mm SLRs for their compactness, speed, versatility and wide range of lenses and accessories, along with lower cost.
When digital took over, camera manufacturers essentially adapted their film camera designs, and we had DSLRs, medium-format digital cameras and digital backs that could be attached to medium- and large-format cameras.
It bothered some people, though, that there wasn’t more new thinking in terms of camera designs. DSLRs didn’t need room for film…
