No they really don't. The Intel HD 4000 alone can push out 1280x800 + 2(2560x1440), as well as 1680x1050 + 2(2560x1440). The fact of the matter is that it isn't an issue of not being able to push out that many pixels; the GPUs can push out that many pixels easily. It's clearly a software problem with OS X's HiDPI support (or lack thereof).
Agree!