Does Incessant Cacophony make Hexblast impossible to cast?

Hello!
As a casual player, I'm making a lich build about Chaos and Curses. So, in a really casual way I'm looking around the skill tree for chaos and curses keyword.

I found in the lich ascendancy the node "Incessant Cacophony: curse you inflict have infinite duration". It sounds cool and it looks like the top tier curses node, deep in the lich ascendancy.
But I read in the hexblast skill small text "Can only detonate Curses for which at least half duration has expired".

So...

Does the "ultimate" curses passive node make completely useless the highest level curse skill? Or am I missing something?

Yes, they mostly killed Hexblast in 0.3 if I remember correctly. It used to not have that requirement (the curse being at 1/2 duration). You could use a Blasphemy aura and trigger Hexblast at anyone in your radius. They deemed that too strong or not what they intended when they created Hexblast and made that change.

So yeah, it's mostly dead. But don't let the infinite duration on Lich bother you, you wouldn't want to use that skill in this state regardless unfortunately.