Yes, rescues require a 100cm x 50cm set up which meant that i wasn't able to adopt from a rescue either when my 85cm x 50cm Alaska cage became free. I got an unwanted and unloved Syrian (Otto) directly from a seller on one of the sites.
I rescue and rehome myself but i'm more flexible and look at the whole picture. I would rehome a Syrian into an Alaska and a dwarf into a Hamster Heaven if the person would also provide the hamster with time, love and care, regular out of cage time and vetenary care if needed.