The concept of this item would be incredibly game breaking - physical dmg and magic dmg do not operate equitably - therefore, armor and MR are not equivalent, which is why having an AD/MR item is not game breaking. If you had an AD/armor item, it would be bought by every AD champion in the game in every match, and basically make ADCs tanks. If you had both an AD/armor item and an AS/armor item, you'd see builds which include 2 AD armor items and 3 AS armor items + boots on ADCs just for the stats. It would seamlessly allow one to itemize both defense and offense which is in and of itself a toxic concept.
Same-name passives don't stack. You know that, right?
Right?
Regardless, Madred's Bloodrazor was never ever ever ever consider OP by anyone despite giving AD, Armor, IAS, AND a hefty chunk of OnHit magic damage. Why would an OnHit/Armor/IAS item be more game breaking?
Also: flat shred auras don't synergize well with the percentile pen from Last Whisper since they get applied first, again making it less than ideal for ADC-types but great for fighty-types.
Conclusion: you are a silly goose.