But LCR are 3 of the 5.1 channels. And LCR arrays were seen back in the 1930s. But is there ANY contemporary video distribution format that supports 3.0?
No an LCR performing arts system is not the same as 5.1 encoded LCR. 5.1 encoding puts the center channel content out of phase so it can be derived as a discrete channel from the left/right audio outputs of a DVD player.
LCR panning consoles sum left and right for a center mono output, but phase remains normal. 5.1 played through an LCR console without a surround decoder results in left&right summed signals canceling out the center channel content. Similar to what happens if you play 5.1 in surround mode without a center speaker.