I'm inclined to agree that this law is something of a tautology. If nothing else, I think it is the wrong way to look at abstractions. I think it was Rich Hickey who said something to the effect of "abstractions are not about hiding, they are about pulling something to the forefront".

It is entirely possible to produce an abstraction over some concept that is capable of expressing the exact same things but brings different areas to the forefront. I think assembly language acts as a simple example of this. You can express all of the same things you can with machine code but it is clearly an abstraction.

Edit: grammar