Why can't we "tag" champions?

Since the day my champion pool started to overflow, I have wondered, "Why can't I tag my champions for their roles?"

When you are looking to fill a particular role, trying to look at every option available is fairly difficult when you have a wall of champions unsuited for that very role clouding your view.

My idea simply is to allow you to Tag champions for roles and when you are in champ select, type in that role in search, there by allowing you to look at your options for that role.