Skidding on a bike probably won't stop you as fast as resistance and a brake because when skidding your weight is typically going more forward... less weight over the back wheel = more likely to slip and brake (see what I did there?) traction which means it isn't stopping nearly as effectively.
Which is why you pop up the back tire and then lock it up, and when the tire comes back down, it is locked and will skid. In that skidding position you can shift your weight to the back which will put more friction on the skidding wheel, so you can slow faster. Also you can do some small turns with the skipping so you dont travel straight distance so much.
I use this method of skipping to slow myself down when im going too fast downhill and there is a stop sign ahead, cars pulling out, etc.
Resisting pedaling can only slow you down so much over a certain distance, and its much harder and tiring to resist pedaling going downhill. When you skip stop you can slow down much faster in a less distance. And I think skipping places less strain on your knees than resisting. And if you need to accelerate again quickly, it is easier to do so after skipping than resisting pedaling because your legs won't be as tired.