The point is that a good functional D&D spell UI doesn't need that many icons.
The upcast spells becoming their own separate icons and spells is not a good design. A 13th level Wizard would have 7 identical looking icons of Magic Missile and every other 1st level spell. 6 versions of 2nd level spells, 5 versions of 3rd level spells...etc. quite a lot of icons.
And then the fact that D&D spellcasters constantly change their memorized selection of spells makes an auto placement on a hotbar in a whatever order a huge pain in the ass. I'm already constantly searching for my spells at level 4. If you have to constantly search a UI, it's bad.
