Once you incur debt, it must be serviced. If you forego revenue via a couple of channels (income tax, inheritance tax), you can either (a) raise debt to replace the revenue you lost or (b) provide incentives so that the revenue foregone is invested (efficiently and judiciously) to spur growth, which brings in revenue or (c) raise revenue via other channels. You can do some combination of the above. The point being, you have fewer options at hand once you incur debt, because default has dire consequences (ask Russia or Argentina), and printing money also has less desirable consequences (indiscriminate tax on everyone including those on fixed incomes and savers).