That is not always the case. Many old schoolers ride with a dominate rear foot, and make more back foot turns. Surfing can be more rear foot dominated too.
I personally am goofy, and my front foot is dominate. I skateboard and surf goofy, so that helps. I find my style is both rear foot in the deep pow, and pretty much neutral in all other conditions. With some of the new dual rocker and tapered shapes ( Never Summer Summit), I feel REALLY comfortable riding basically centered in the deep pow. It is truly revolutionary.
The whole sliding on the wood floor trick works for many. More athletic dudes can go both ways, and they should go with what feels more comfortable when skating to the lift, or if they ride a true twin etc....
pray for snow.
Making back foot turns doesn't indicate dominant foot. Dominance is more about the side of your body that is use to being the balance point and start of a side of the body from left and moving through space. For instance a back foot rider maybe using the back foot to kick the board around but its in an attempt to allow the front foot side of the body to travel in a certain direction. In back foot steering a person has to unweight the back of the board to lighten up the back of the board to be able to move it. at this point they aren't balancing on the back foot they are actually balancing more on the other foot.
When talking about surfing or say droping on a skateboard into a pipe a rider has to get play a delicate balance of not to far back or forward. They need to get their board/deck to match the angle of the wave or pipe wall. to far back and they bannana out or two war forward and the nose augers in and over the nose the rider goes. The movement toward the nose and toward the tail doesn't indicate dominat foot. Just balance point along the board that is dictated by the type of substance being ridden, and slope of angle being ridden on.
SO in replay what is meant by dominant leg is either the left or ride side that a person feels more comfortable about moving through space first.