Why was early cdr gutted?

Pre patch I could quickly get 20% cdr from just masteries and

If I rush Ionian boots now It's just 10% thanks to nerf and mastery removal.

now there are only 10% and 20% cdr options unless cdr runes are used, and teh extra cdr on boots and mastery helped when your 5 essential item build has no cdr items, or at least nothing for early game.

I just dont get it.