There's a million and one things that can go wrong a cnc is a tool no different than a planer router or drill press. At the end of the day its as good as its opérator. You could put the wrong bit in a 1/32" bit oversize would completely ruin the whole thing. Then you got the glueing up process that can be tricky and there's no machine for that. Then finishing where another million things can happen. And some times every thing goes right but the guitar still just isn't right.