Because Colombia and Paraguay have a history of paying their sovereign debts, haven't had the economic history Argentina has, they don't have a cepo, and perhaps most importantly is their populations savevon their currencies/trust their currency.Why in Argentina's case floating peso would rise to million.
While CO & PY floating currency rose only to 4000 & 7300.
Is it possible to kill inflation without dollarizing? I think so, it just takes longer. You could change the organic charter of the BCRA and proceed with Milei's reforms that are generally pro-market, and you could implement a positive real interest rate, but it takes more time to do this.
Other countries have avoided dollarization to fix macroeconomic problems, but I believe Milei's motivation with dollarization also is to set a trap: it will make it socially unacceptable should he lose in 2027 to abandon dollarization since the population will be reluctant to return to the peso, therefore institutionalizing some of his reforms.
We'll have to see, I'm still not entirely sure they'll be able to dollarize at the rate things are going.