> Since their dream is a Digital Currency where every penny is tracked

Scroll up. They already had that.

> The actual ledger that comprises Bitcoin could be run on a Raspberry Pi, no problem.

If no one else were doing it on more powerful hardware then yes. People used to mine bitcoin on old laptops.

> The obscene computing power of miners is simply applied to solving a random mathematical puzzle to determine who will get the award for doing the trivial task of adding transactions to the ledger.

It's about doing it faster than anyone else. Adding transaction to the ledger is the random mathematical puzzle. They're not separate.