Shield Upgrades using the Smithing Table

This might already be what Mojang is planning, based on the combat snapshots, but in case it's not, I wanted to throw this idea out there.

In the latest combat snapshot, adding a banner to a shield increases the amount of damage it can block. This is obviously a place holder for possible future shield variations. 

Where my idea comes in, is in how exactly these different shields are created, not by simply crafting a shield with a diamond, instead of an iron ingot, but by using the Smithing Table to upgrade a default shield with a diamond to create a diamond shield, and then upgrading a diamond shield by combining it with a netherite ingot inside the Smithing Table to create a netherite shield.

Each shield would obviously block more damage than the one that is used to create it.

The idea of different kinds of shields is nothing new, but I haven't seen anybody bring up the idea that the Smithing Table would be used to create them, giving it another useful function.