@BIG-BENNIS-MAGIC we don't talk about purging mercies from the game,we're asking for a nerf,it doesn't matter if you did scout them or not same for aa,their activation radius is just too big,you need to keep your aa too close to the acu and even in that case you'll kill at best 3 mercies only and no,they are not costful.
the only bad thing that might happen when you build them is the early stage when your opponent is going t3 air in any other case it's efficient to build them(considering they will connect in the end).
also that's the reaction you'll get when sniped by some only aeon boy.https://www.youtube.com/watch?v=obCHtnfKRjk&ab_channel=TotallyJustABean.
live with that.