I don't see a practical use for a machine like this in the average frame shop. For large quantity assemblies, maybe. But the logistics of adjustment to fit different frame sizes, maintaining consistent accuracy on the corners during assembly, and maintaining calibration of the assembly equipment could pose a problem. Aluminum doesn't have much "tooth" against itself as wood miters do and I can see a possibility of misalignment problems and consistency of tight even corners with the aluminum.
There is another thing to consider: when building an aluminum frame, if you are going to load the frame with art/mats/glass, you usually don't completely assemble the entire frame. I assemble 3 legs tightly and align the 4th side to install the hardware to the 4th leg only, then slip the 4th leg out of the frame to load the frame package. Then the last leg is tightly assembled. there would have to be some allowance made to get the frame package into the frame before finishing the last side of the frame.
I would think that some kind of simple clamping system for one corner (at a time) would function better along with a pneumatic screw driver to set the screws.
It isn't a complicated procedure to assemble a metal frame, I acquired the knowledge of assembling metal frames when I was 5 yrs. old playing with my Erector set! Of all the movements required to build a metal frame, the alignment of the corner would be the most critical part in my opinion. A non-slip clamp should take care of that portion easily.
Framerguy