Comment by myself248

They're not combining anything, they're sending 19 copies of one signal down 19 strands (with some offsets so they interfere in awkward ways), applying some signal processing to correct the interference which they say makes it realistic, and declaring that they've calculated the total capacity of the medium.

What you do with it at the higher layers is entirely up to you.

But, ethernet could totally do that, by essentially demuxing the parts of an individual packet and sending them in parallel across a bunch of links, and remuxing them at the other end. I'm not aware of anyone having bothered to implement it.