Ghost Mourner & Moonlight Chill Ruling

I often hear this card is absolutely garbage in TCG for being a trigger effect instead of a quick effect, or a pseudo quick effect like in the OCG(In the sense that it can be chained anywhere in the SS window).
I am not really sure why it is so bad, It can still be used to stop on summon effects on your oponents turn, no? for instance, bacha, SE ash, etc... is it because the ease to dodge if the target monster has a quick effect, but thats not that different from veiler in that regard, and both are useless during your turn, what am I missing that makes this card so terrible?

(Edit) Also I guess I should ask If it's worth swapping for any card what would you put in this flexbox instead, maybe 3 thrust or 2 thrust and a high impact trap like evenly?
My HT lineup is 2 nib, 3 ash, 3 veiler, 3 imperm, 2 ogre, 3 mourner