We've already had a discussion regarding the benefits of tiled rasterization above, so I won't go into details. But there are some myths that need dispelling:
No game is stupid enough to render things that are behind the camera. At the very least games check whether the bounding box of an object intersects with the camera's view ("frustum") and discard ("cull") any objects that don't. See "frustum culling" for details.
In fact games use a series of finer and finer (and thus more expensive) mechanisms to determine whether a triangle needs rendering. So even if an invisible/occluded object is rendered it will be discarded, either by game engine specific optimizations, clipping or the z-buffer. The earlier a primitive is discarded the less computationally expensive it is.
In conclusion, there is not nearly as much left for a tiled renderer to cull as one might think. Yes, it is useful, but don't get carried away by thinking that it can free up large amounts of resources. Tiled rasterization has been used in mobile devices for a while now, with the intent to save bandwidth. How useful bandwidth savings on a card with High-Bandwidth-Memory are is left up to you to contemplate.
On a side note: If a game would actually render objects behind the camera, you would see them. Been there, done that.