If the Anvil can be enchanted with Unbreaking, why not Mending too?

I have always put Unbreaking on my Anvil. It both has a meaningful effect on saving my resources, and is a unique quirk to this game which very few people are aware of. I've done that since the anvil was added. In my world, I just went and got a bunch of mending books, and out of curiosity, decided to see if Mending works on Anvils. Logically, this enchant has no reason not to be applicable, the object has some form of "Durability," and it already does work with Unbreaking. So why not give it the behavior that any other enchantable has? 

The caveat is understandable, the Anvil doesn't have actual durability values at the moment, I haven't looked at the internals of Minecraft since Beta, so I have no idea how in-depth the system is, but I do acknowledge the Anvil durability system would have to change, and the block texture would need to be stored as NBT rather than separated as the "Damaged Anvil" acolytes. 

Though, the outcome is more logical, and generally better for extensibility sake anyway, and would give players another task to do in their homes.