Very cool!

That's a good point, lots of transceivers do encode/decode signals with multiple levels. I was only thinking about the processing and storage of data. Even a qam-64 symbol needs to be converted to binary to do anything useful with it.

You can get more storage/bandwidth by just adding more binary bits. To achieve the same result with a ternary system would require way more cost and effort.

There isn't really any advantage to adding a third symbol when you can just use more binary digits instead. With two binary digits you can have 4 values, and with 32 digits you can have billions. Sticking with binary allows us to build electronics that are fast, cheap, and reliable.