It's extremely difficult to find a system that can have very low to no fees and that isn't simultaneously open to abuse by a script-kiddie... unless that system doesn't actually store a ledger but rather something like ...balances which shift.

Actually even then you can spam it by creating a lot of balance addresses that would require XX bytes to store, just by sending a no-fee tx of 1 satoshi / duff to a veeeery long list of random addresses. So, I really can't think of how you can make a promise of zero to very low fees and infinite scaling when you are also opening yourself to an attack vector.

But then again, I'm not the coder here.