you give a nod to the solution. If we have an undamped oscillator, or a system with a tendency in an undesirable direction, we can damp it.

And currency (given that we make it up and have a reasonable degree of control over its worth and distribution) does not have to be a static cumulative ledger

Any solution needs the damping function to be intrinsic to the system, rather than tacked on as policy. Policy ends up being dictated by the powerful, so if your system's only check against runaway wealth accumulation is policy, eventually your guardrails will be demolished. It might not be today, it might not be tomorrow. But eventually, self-propelled wealth wins.

There are models of currency that try to include such dampening intrinsically (Tankies love talking about various experimental forms of currency as "labor vouchers" to try and sidestep the "moneyless" pitch of Communism), but I've yet to see one that really addresses the "wealth begets wealth, hierarchy begets hierarchy" problem.