The way I see it, why do people write poems instead of prose? Because poetry imposes an additional structure of some kind on the words, a rhyme scheme, a meter, a syllable count. Paradoxically, by limiting the ways the writer can express himself, new things come out of the composition as the poet exploits that structure.
Film does something similar. Every type of film, paper, processing etc. imposes additional limits and structure on the photograph and the photographer exploits that structure and limits in the form of color palette, grain, resolution, etc to say something.
You can make a synthesizer that sounds just like a violin. You can make one that sounds almost exactly like a violin but has small tweaks to make it even “better,” yet people will still line up to watch a violinist rub horsehair over catgut strings stretched over a piece of wood, because the musician exploits that structure and limitation to say something.
I think I see the allure of the “toy camera” in this way too. I am not a devotee of toy cameras myself, but when one uses a very flawed camera, that imposes light leaks or blurring you can use these limitations to say something. For me, toy cameras are too limiting, but I guess I see the point.