Because there would be no point using any two handers or dual weapons if it gave nothing except the loss of a shield defensive value.

Mmorpg and video games are based on a logic that doesn't defy basic physic rules.

Of course magic comes and game design adapt things. Because games with no logic and magical nonsense put everywhere are underplayed korean games, at most.

The game wouldn t be played with no common sense or logic. Because players would just be "wtf".