No such thing in the real world? It's not a broadcast resolution. Who gives a toss about broadcast resolution? Who shoots only in the resolution they're broadcasting in? You know not of what you speak. I suppose Arri's 2.8K or 3.2K don't exist either.
The 2.7K resolution is baked into the Ambarella SoC which in most applications uses the centermost pixels on the imager. When you're bandwidth limited on the processor as the A9 is, managing the compression of a 2.7K image will yield better results than trying to do the same at 4K. How exactly would that be a gimmick?