Ski construction is probably far more important than the geometry of the sidecut. I find that a stiffer ski will hold better on ice than a softer ski. As novice and intermediate skiers generally will be skiing a softer ski, it is only natural for them to not be able to readily hold on ice. Whether one's skis are properly tuned also play a big role in their ability to hold on ice. Tuning involves, among other things, sharpening the edges.
Sharp edges are crucial to effectly coping with ice.
The Early Edge Grips the Ice. Finally, holding on ice is very much a function of the skill level of the skier. Crucial is engaging the edges early in the turn. For the intermediate skier, this is easier said than done. Most skiers will, to effect a turn, flatten the skis so they will start drifting and sliding down hill and the start rotating the skis.