Undo Button (Data)

I wasn't sure exactly where to put this, so I just chose gameplay :p sorry if it's in the wrong place!!

I don't know why I never asked earlier, but it seems that whenever you purchase an item and then undo it, it seems to also undo your health. I think you're literally restoring that champion to an earlier state of time. I asked a friend about that and he said it was intentional by riot, but isn't that kind of inefficient? I don't know much about how the data works, but it seems like it would be easier just to implement a stack, and put items bought into the stack. Once you leave the base, they'd transfer over to the data structure that holds items, and therefore you wouldn't be losing health! Random question, but I'd love to have it answered :)

Ps. If it wasn't clear, a stack would be the best for an undo button because of the last-in/first-out way that it works. Lower time constant.