But then the question becomes why can't Argentina let the ARS float and live with that?
Well, for starters you actually need to have dollars available for everyone that wants them for this to work, and you basically would have runaway inflation worse than we have now as companies and people would trade in all their pesos for dollars knowing the peso would be worth less tomorrow, next week, next month, etc.
When the Peso Ley 18.188 and Austral ceased being legal tender the largest notes in circulation were 1 Million and 500K respectively. Something similar would happen with a market determined exchange rate. You basically cause a market driven dollarization as the exchange rate would skyrocket, salaries plummet, and GDP goes in to free fall.
Milei is pro dollarization, but not at any cost, and while a free float is a way to basically dollarize the country instantly, it creates a socio-economic pressure cooker because those with dollars stop spending beyond say food/shelter, while those without dollars lineup at Dia to buy food that is repriced every hour like in the 80s and cut the streets because you can live on 3 facturas a day.
Why Dollarization? Has Zimbabwe got any better?
What dollarization does is provide stability; when countries dollarize, they can no longer issue their own currency, which in the case of Argentina would prevent us from printing pesos to cover budget deficits or have a domestic debt market that is easily manipulable via cash injections from the government. With a dollarized economy, the monetary supply is broadly determined by the Fed in the US, but domestically in Argentina it's more finite, i.e. you can only spend what you have, and since you can't print dollars, you have to obtain them via debt issuance in dollars, or via income, i.e. taxes in dollars.
Now, dollarization is only a magic bullet for inflation/macroeconomic woes for as long as a country is willing to take measures to address the underlying problems. Milei's argument is that dollarization + macroeconomic adjustments will do things to stabilize Argentina's economy and make growth and investment possible. Zimbabwe for example still suffers from macroeconomic problems and the country reintroduced the ZWL in 2019, so it's not fully dollarized. The Mileista argument would be that dollarizing under Massa would only fix so much, you have to change a country's habits more broadly for it to work overall.
