The volume/surface area problem is the same reason why you generally don't see massive single celled creatures. Also, it's why smaller people can be pound-for-pound stronger than heavier people (muscle strength scales with regards to muscle cross section, whereas muscle needs to fill out the whole volume).
Leverages also have a lot to do with greater apparent strength in shorter athletes, though that varies by lift.
For bench press, short arms are an advantage, as well as where specifically the muscle anchors in the limb. Similarly for squats.
For deadlifts, the situation's slightly different: long arms help in that the bar needs to be moved a shorter distance, though femur length still benefits by being short. There's also femur-shin ratio, and how that plays with angles.
