Zoro with the same enma cut kaido but just did a small damages. If enma is the greatest PU of all time then kaido should be dead right now. Understand what is the difference? At the end, it depends only on Zoro's strenght and haki. The more stronger he becomes, the more enma will be deadlier.
The stronger Luffy becomes the deadlier his fruit becomes, the stronger Sanji becomes the stronger Sanji+raid suit is.