The whole concept of hunting sheep by climbing and hunting from the ridge lines, (which certainly is not "wrong") increases the chances of some general concerns from the standpoint of most effectively hunting sheep ,
1.) greatly increases the chance of having to make a "snap" judgment about the legality of a particular animal;
2.) increases the difficulty of evaluating ALL animals in the group; many of which may be out of view because of the terrain,
3.) because of the closeness when initially "discovered" options regarding the ability to achieve the best position for shooting are often greatly reduced,
4.) greatly increases the amount of disturbance to the animals encountered, (two or three groups of sheep hunters hunting the ridges, in a general area, can't help but keep the sheep moving).
These are but a few of the reasons the effectiveness of sheep hunting is generally reduced when done from ridge lines. Thought certainly not true "100%" in all situations, certain very few exceptions.
"Glassing" sheep habitat from terrain where sheep are not generally found pretty much eliminates the four concerns listed, and, increases EVERYONE'S chances for success.