User blog comment:Lukeatlook/Pyro's Item Overhaul 5 - Supports and the CDR Overload/@comment-5266525-20140719194404/@comment-1330314-20140725090532

The problem with a soft cap is that, inevitably, it'll lead to similar issues of stat wasteage (you get less and less CDR), except it being not clear-cut means you don't have an immediate indication as to when it's not a good idea to buy CDR anymore. On top of that, despite the wasteage, you'd still have to account for extreme situations such as someone buying six 20% CDR items. This might not even be that much of an extreme case, considering supports are required to rush CDR items now, and would likely have to define their build purely around CDR items. Supports already use two to four item slots to fill out on cooldown reduction, so allowing them to itemize for it without a cap wouldn't help them out as much as you think.

I think the issue of "big ticket" CDR items is something you'd want to solve on the items themselves, and not through a system overhaul that is likely to break more things than it would fix. Athene's is an item with a lot of different issues, with its generous CDR being just one of them.