Not entirely true, it's like a curve. The more STR the more your amount of SP plays a role.
Actually, the more SP, and the more STR will dominate.
besides, It's advisable to get SP increasing gear (in slots where you can get it) such as lich's, mid headgear and top.. then pump STR/DEX/VIT and leave INT at minimal, if you're planning to main efist.