> I have seen people mentioning difficulty on problems where you need to mentally rotate a cube, but I can do that just fine - it's just that I don't "see" or "picture" the cube, but I still have the concept in my mind of the cube being in a certain orientation and that suffices to solve the task.

As someone with probably some form of aphantasia, a cube is fine because it’s a simple shape with well defined simple mathematical rules that is easy to abstract and rotate. It gets more complicated with complex objects and that’s where visualizing things really matters. Here’s a question, can you accurately visualize a loved one’s face, see it in your mind and describe all the features if you were for instance talking to a police sketch artist. I couldn’t even do that for my daughter or my wife.