This is true, but the complication with developing countries (and I believe this is what the person you’re replying to was implicating without elaborating) is that more often than not, these countries also take on foreign loans, usually denominated in dollar.

If you take on a huge sum of dollar debt, this effectively limits the fiscal space of countries even with monetary sovereignty, because institutions like IMF will often impose demands like austerity measures (e.g. “cut back fuel and electricity subsidies”) to limit net public spending. You don’t follow the rules, you don’t get the loan, and your people starve.