Any slider worthy of the name can support the half the weight of the vehicle (or more) at a single point. Whether that is a jack, a stump, or a pointy rock is irrelevant. I don't personally have Shrockworks sliders, but if they didn't work you would be able to find dozens of complaints on this board.
It's possible the videos you are talking about were with sub-par homemade tube sliders? Link?
That said, they are sliders, not slammers. It's possible they will dent if you slam down on a point. But jacking should be no problem, as long as you have the proper jack cradle to keep the jack from slipping on the tube.