Riot, stacking the same item over and over again is not compelling gameplay
Edit: If you disagree, at least leave a comment as to why. Simply downvoting and leaving is unhelpful.
Players are making extra use of the Transcendence Rune by stacking items like Frozen Heart or Black Cleaver.
I can't think of any compelling reason to leave it the way it is. It would not hurt normal or intended gameplay to make the CDR from every item unique to the item (so that having 2 of the item won't give twice the amount of CDR). And it is entirely unfair for champions to be able to build tons of tanky stats while still retaining high damage output.
This is a case of players optimizing the fun out of the game. They found an unintended exploit in the mechanics of the game, and they are doing gamebreaking stuff with it like being able to assassinate opponents while still being near-impossible to kill. Stacking the same item repeatedly is not compelling gameplay. And I highly doubt it was an intended effect when you introduced the Transcendence rune.
) it is absolutely essential. So I feel that if they are going to reduce the effectiveness of duplicate items that they do so in a matter that takes these niche builds into consideration.