I agree with the view that the iGPU in all models can easily produce all the visualisations. They are really simple models. Compare the visualisations with the games that can be played, like Beach Buggy Racing.
Available memory could be an issue, as it's shared between CPU and GPU. I don't know if swap is used, probably not, but disk performance might be another issue.
But my best guess is that available storage space is the limiting factor. I recall this was doubled along with the AMD processor. I suspect there's almost no available storage on the older boards and they've been removing everything they can under the covers. I wonder what the health of this storage is, it will wear out.