Why do you want to have a champion that has no innate cc, get cc from an item? What if that was given to a Yasuo with a specific item...
Opposing Wind
75 AD
30% Crit
Unique passive: Opposing wind: Yasuo's targets face strong opposing wind currents when hit with your AAs and/or abilities, slowing them for 30% for 2 seconds.
How broken would that be? It would be quite broken, wouldn't it?
Or give a similar item to a Zed/Talon/Rengar/Kha'zix... Zed and Talon have no innate cc, ok, zed has a mild slow that only applies on his shadowed E and only for 1.5 seconds, Imagine Zed and talon have an item that slows you indefinitely for as long as they damage you, imagine that on Talon's bleed. Imagine that on a Darius, a JUGGERNAUT that's supposed to be slow and kiteable. Imagine that on him, his bleed lasts for a LONG time, and each hit or Q refreshes it, imagine getting hit by 1 stray Q, you are then doomed. Or, even worse, imagine this item on Draven
Crippler's Axe
75 AD
30% crit
Unique passive: 20% lifesteal
Unique passive: Draven't AAs and Spinning axes slow targets hit for 40% for 2 seconds
Imagine a draven with that thing building crit, IE-PD-ER and that. Try to even fight that.
Or give a similar item to a Vayne and try to fight her.
Mordekaiser DOESN'T have an innate cc, iirc he never had cc. There is a reason for that. If you don't agree with it, you should probbably rethink your priorities and why you main him. If you haven't mastered his kit in way that allows you to play him effectively with his kit as it is and you revolve around a particular ITEM to make him viable, you never had your main, you never even mained him truly.
If you main a champion and dedicate to a point that your name itself in game reflects it, and you can't play that champion with their kit alone without depending on a particular item to win, you never master the champion, you only like that champion because of how he interacts with items, not because their kit and concept is thrilling for you to play and master.