Another big reason for Scrog is to control the height of the plant for those who have limited vertical growing space. Also, scrog allows for less plants while still maximizing yield. The strains which are best for scrog are usually the bushier kinds. NorthernLights can be an example as one that comes to mind.
There are many good tutorials on the net to get a better handle on scrogging, just do a Google search.
Adieu