Wit's End Not a Magic Pen Item? (Overlooked?)

I've noticed two new filters in the new client's Item Set Editor; Armor Penetration and Magic Penetration.

Armor Penetration lists; Serrated Dirk and upgrades, Last Whisper and upgrades, Lord Van Damm's Pillager, and The Black Cleaver. Although The Black Cleaver doesn't function the same as Lethality or Bonus Armor Pen, it makes sense because it reduces your target's armor by a percentage for each stack.

Magic Penetration lists; Sorcerer's Shoes, Haunting Guise/Liandry's Torment, Void Staff, and Abyssal Mask. What I don't find listed is Wit's End, which functions in a similar way to The Black Cleaver as far as magic pen. "Basic attacks steal 5 Magic Resist from the target on hit (stacks up to 5 times.)" After testing in Practice Tool, I confirmed that the MR is indeed removed from the target and applied to the user. Does this then classify Wit's End as a Magic Pen item?

(To Riot: TY for the return of the Item Set Editor!)