I was a lifeguard through college, and one of the pools I worked at had a slide. I had to make more saves at the bottom of that slide than everywhere else combined, because the force of the water coming off the slide caused a bit of a whirlpool. Small children (basically any child who was too short to have at least head and shoulders above the water when standing on the bottom of the pool) simply weren't strong enough to get out of the whirlpool by themselves.
So what I'm saying is: Yes, parents, please stand at the bottom (off to the side, not directly in front), waiting for your child to come down, so that you can help him/her away from the slide.