Earlier quoted context omitted.
Dragging your foot on a skateboard leaves your other foot planted on the board, meaning the board is vulnerable to catching on any crack or edge while carrying most your weight, which will send you tumbling. You can drag your foot exactly the same way to lose speed on skates by dragging one perpendicular to the direction of travel, while your other foot is still perfectly capable of jumping you over any cracks or edg…
To shed some lights on why power sliding is so unreliable, doing so requires to be familiar the surface on which you’re attempting it. Being familiar with it means that you basically failed to and fell down multiples times before getting it right, which already requires a good skill level. And you cannot assume that power sliding on a surface will be similar to another one that looked the same because a slight change…
See my other comment.