Chainsaws are only effective for cutting wood. Not much else.
Excuse me sir, but dare I say that this point seems to be conjecture?
What evidence have you to support such a claim?
I don't know the exact metrics we would choose to judge an effective kill, be it lethality or viscera. But I Imagine a chain saw could get the job done emphatically. I mean if I pressed a chain saw to someones face or neck, would it not slaughter them?
I have a hard time imagining if I go to chain saw someones face that somehow that persons face is more solid than a 4x4 post or a tree. Even if it was, the chain would most likely rip their features and blemishes into pink ribbons before getting mangled in their rock hard teeth and eye sockets. A fate probably even worse than death, at that point I'd have to resort to using a sledgehammer or some gangster shit just to mercy kill.