You are right to a degree. You can prewash your fabric, It removes chemicals, shrinks the fabric, checks bleeding and how the material acts after washing, Does it stay soft, pill, get dull. You will still achieve a crinkle look if you use cotton batting because it will do just enough shrinking to get the desired effect.
I always wash, dry and fold fabric as soon as it comes through my door and get it into my stash. As I need fabric I cut the amount I need off the stash fabric, dip in liquid starch, damp dry and press.