Strength was a core stat in Diablo and Diablo 2. It was tinkered with in Diablo 3 having been replaced by Attack during development then brought back later in development.
Strength is a core stat in Diablo 4. In Diablo 2 it was used to increase damage and determined what weapons and armor could be equipped. As it is a core stat in Diablo 4, it's could follow a similar model to the earlier games.
Strength has always been a key stat for classes such as the Barbarian where each point would add
- +x to Armor.
- +x to Barbarian's damage.