Not true. I'm overweight and I easily outroll anybody smaller and skinnier, since I have more mass to overcome air resistance. In very crude terms air resistance is based on your sillhouette which is two dimensional, while gravity is based on your mass which is three dimensional. An extreme example is a mouse which can fall from a great height without getting killed since his surface area is large relative to his weight, while a person can be killed by a fall of only a few metres. Or better,think about throwing a table tennis (ping-pong) ball vs a rock of the same size, or dropping a feather vs dropping a dime.
RGC