Used to do this. I had issues with either the audio or the video feed randomly dying, though, so I ended up finding a way to make HDMI+USB work when I moved.
More reliable, but now that I'm starting to think about reorganizing my office, copper will no longer do for 4K120 as that'll go over the 5-meter limit. And an optical high bandwidth HDMI+USB setup isn't cheap.
Upsides and downsides...
Wasn't it originally a huge public undertaking? It was my understanding that the rails and CN began their lives in public ownership before being privatized.
Did I misunderstand things?