Why does every use violent dead without 40 int? Please

Ok. So I'm trying to figure out my passive tree. Everytime I look at examples. They always put violent dead in a socket to the far left of the starting area. They put this there without the 40 int in radius. Why not take the 40 int and activate half of the gem. I believe it affects zombie slam. They also have another violent dead with the correct 40 int somewhere else, Two violent dead gems do stack correct. Can anyone please shed some light on this.

And if they don't stack. And they don't use 40 int. Wouldn't it be better to replace that second violent dead with to dust

the 40 int only has to be in radius, it's not required to be allocated

Omfg, no way. Lmao ok, that's awesome. That helps a bunch! Thanks!!!