Why aren’t DH’s allowed to play in NL baseball parks?

I never got that rule, well….i really just finally realized that rule very recently. Why does the national league not have a DH? i dont get it…

A better question should be “Why do they have the DH in the AL?”. Remember, the rules of baseball never included a DH and it was the AL that made the decision to stray from the rules of the game. Therefore, the DH is never used in NL parks during inter league play.