ADAT Lightpipe supports up to 8 audio channels at 48 kHz and 24 bits - all using standard off-the-shelf Toslink cables and transceivers. MADI can do significantly more.

Let's not pretend surround sound is a nearly-impossible problem only HDMI could possibly solve.

I... think you might be proving my point for me? The ability to have a single cable that can do video AND a bunch of audio channels at once is amazing for the average joe.

Don't get me wrong, I use optical in my setup at home & I'd love to have more studio & scientific gear just for the hell of it, but I'm the minority.

I'm not trying to defend the HDMI forum or the greedy arsehole giants behind them. The DRM inbuilt to HDMI and the prohibitive licensing of the filters (like atmos) is a dick move and means everything is way more expensive than it needs to be. Was just pointing out that parent's comment was reductive.