RVT comes into it’s own with landscape. With landscape, the engine spends a lot of time deciding which part of which texture to show the player, because in a sense, it’s blended dynamically.
So it’s much more efficient to bake the whole thing into a big render target. Then, the game is just using memory instead of processor power.
If you have a texture placed on a mesh, why bother copying that to a render target to display it? You already have the mips system which works great.