Sculpt Mask By Vertex Group

The idea is to be able to create a sculpt mask, with varying values. Essentially this would be like hiding parts of a mesh in edit mode for you to sculpt, but instead it's not just all or nothing and applies your sculpt mask based on a vertex group selection. Why not just paint a sculpt mask?

1. Because it's easier to view the vertex group.
2. You can perform more operations on a vertex group than a sculpt mask.
3. You may already have vertex groups to use in order to create one from.