It's summarized nicely with the key points in this CNBC article:
For many Afghans, this week has laid bare the worst-case scenario for a country running on legacy financial rails: A nationwide cash shortage, closed borders, a plunging currency, and rapidly rising prices of basic goods.
In some ways, it’s a perfect test case for the usefulness of bitcoin and other cryptocurrencies. CNBC spoke with several Afghans who are using crypto to learn how they got into it, how it’s helping them, and barriers to further adoption.
When legacy financial systems fail due to any reason--war, economic and political instability, or a shaky economy, etc.--cryptocurrencies become valid alternatives. You can buy Bitcoin, which could be volatile, or cryptocurrencies pegged to government-issued currencies such as USD, EUR, JPY, etc. These are known as "stablecoins," which you have total control over.
At the end of the day, you still need some legacy bank to cash out your cryptocurrencies. Or, you may use services and buy goods from places that accept cryptocurrency as a form of payment.
For people who live in unstable regions, cryptocurrency could be better than legacy banks.