Clicked on the demo "What caused the fall of the Roman Empire?" and immediately saw the same inadequacies I've seen in every other system like this: any attempt at visualizing a point ends up being absolute nonsense. Graphics and charts that confuse more than help, or even contradict what is being said.

It ends up being a hurdle I don't think these services can surpass, given these systems understand nothing, and have no spatial reasoning. Any of these systems that claim to help explain things visually end up being a huge liability for the learner and I would never recommend them to someone.