Oh, I see. So the mind-blowing solution is the Zk-Snarks. Dash is more like a protocol-level coin mixer. Miner takes all the transactions, shuffles them into a single big grab bag and says 'these are the inputs, these are the outputs, good luck tracing'.
Theoretically if you ran a super-node like a miner and kept your own separate record over time, you could trace everything. So it's susceptible to man-in-the middle attacks (read-only) but trace-less otherwise (assuming decent transaction volume).
You could also still do probabilistic tracking, but you would need a lot of transactions to draw a clear line between two addresses.