Why do I need to finish "The Artificer's Pit" on LEVEL 20!

I have loved all the Diablo games but I can’t finish the VofH compaign BECAUSE I CAN’T GET PAST THE REQUIREMENT OF FINISHING “THE ARTIFICER’S PIT” IN LEVEL 20!!! I have don’t it on Normal (Level 1) and Hard (Level 5) but I am just not good enough to be required to do it on Level freaking 20!!! Is there anyway to continue or just give up? (And yes, I am probably older than most Diablo players, but I love the games as long as I am not forced to play at what I consider an extremely hard level.
Sorry. I just read on another site about Diablo that the Artificer’s Pit is not actually part of the “campaign” but something to achieve AFTER the campaign story ends. But then the icon in the game should not be yellow which indicates part of the main campaign IMHO.

Are you confusing Pit Level 20 with Game-Difficulty levels 1-4 and T1-T4?

You can do the pit to gain access to higher difficulty levels.