Why can't wizards cast healing spells in so many settings? It seems kind of arbitrary. I'm really not even sure why Dungeons and Dragons did it originally. Wizards can alter reality in such dramatic ways, why not mending torn flesh and broken bones? Even outside of Dungeons and Dragons this same trope get recycled a lot. Savage Worlds Fantasy companion even has it as a rule. I'm not saying wizards are underpowered in every setting, mythology, or game system, just asking why this trope? Is there a really good reason in the DnD Universe?