Camera-to-subject distance affects DoF, but do you change you change your camera-to-subject distance so you can get a different DoF? Not me.
Focal length affects DoF, but do you change you change your Focal length so you can get a different DoF? Not me.
Format size affects DoF, but do you change you change your Format size so you can get a different DoF? Not me!!!
Circle of confusion affects DoF, but do you change you change your circle of confusion so you can get a different DoF? Not me!
Aperture affects DoF, but do you change you change your aperture so you can get a different DoF? YES YES YES
Have you EVER changed ANY of those factors (except for aperture) just so you could change the DoF?