5.1 audio channels is all you really need.
I would be interested to know the actual audio setup of most video watching ... I suspect that even if you ignore whatever (probably huge?) percentage is on mobile, that much of it comes out of whatever TV speakers are being used. Even my 7.1 receiver is down to a single laughable channel, because I've not been arsed to fully set it up and a wire is loose.
And the rise of phones means there's a lot of stereo or even mono.