Because it's going to be so stupidly strong on release (seriously, look at those stats for it's price. It's laughable) that Riot will pull a "Sejuani" on Ad assassins 
and then nerf the item.
Riot doesn't understand that this item came too late. Back then ad assassins needed this item, nowadays they are in a very good spot and this will push them over the edge. The only person that needs this still is maybe kha'zix.
maw is broken, ghostblade is way better than before, Simitar is WAY better than ever, deaths dance got some buffs. why do ad champs mid need more items. to kurb stomp mages even harder?
The item won't get nerfed. If you do 2k damage and they don't die, you'll finish with a measly 590 damage, mitigated by at least 30%, bringing it down to 400. Its not any worse than Lichbane.
400 damage is strong, but its not OP for a class of champions they're going to nerf and tune to this item.
This isn't going to be a champion->item nerf.
They're going to nerf all of the champions that see a rise and then balance the item in order to use it as a crutch.
