The biggest weakness of a slice is passing shots. If you have a hole in your game, e.g. high bh, good players will find it and pound it all day.
A slice doesn't dip, therefore the passing angles are much narrower, and the ball is easier for the net guy to handle... mostly a straight in straight out type of shot.
the topspin shot, with today's racket and string, can have a crazy dip down to the net man's feet.. Because the bh loading with the ISR is deeper than the ESR loading of the fh, the 1hbh actually should have more spin than the fh.... hitting a high ball down, combined with the spin, this can make the net man feel like this ball is dropping straight down on him... not a easy ball to handle.