Except something can be fungible AND public which, in terms of unbacked monetary properties is far more optimal than being fungible and obscure.

In bitcoin, every coin address is visible, its balance auditable and its continuity with every other address explicit. That transparency is UNIVERSAL and SYMMETRICAL. i.e. it isn't restricted to keyholders, everyone has the same view whether you're a payer, payee, network participant or non-participant.

That's fungibility.

Dash further enhances this almost-perfect monetary token so that the coin supply is highly resistant to regular pattern detection, thereby optimising transaction anonymity WITHOUT recourse to torpedoing the blockchain's transparency.