I think it's not recommended because the eggs are actually small enough to get crushed. If you have extra quail eggs you might as well try it, don't mix chicken and quail eggs, and remember they need game bird starter when hatched.
I used a Silkie hen to hatch 8 quail eggs and never again. She didn’t crush the eggs but couldn’t keep up with the tiny chicks and even lost one. I immediately pulled them and brooded them myself.