It's another way to convert dollars to pesos at the CCL rate rather than the official. Western Union seems to be the simpler solution at the moment but it's always good to have a few options at your disposal.
I know they don't literally buy dollars, but it's a way to get the CCL rate.
1. You take dollars and exchange it for DAI on a US exchange.
2. Transfer your DAI to Buenbit or another Argentine exchange.
3. Sell your DAI on Buenbit, and receive pesos at a rate near the CCL.
Usually there is an implied double conversion. USD -> BTC -> DAI.
Why wouldn't you just buy bitcoins for dollars and sell them or pesos instead?
Stablecoins are for storage.
Personally, I'd use BTC. If you wanted to eliminate the risk of volatility during the 45 minute transaction time then I guess DAI would be an option.
Anyway my point is that it's a way to exchange dollars for pesos at higher rate than the official or the blue. That's why I assume On the brink is inquiring.
I've used Ripio, I haven't given Buenbit a try before. Check out https://coinmonitor.info/ for all the current rates.
I did a quick comparison and today the best rate was with WU with 82.82, followed by the combo Coinbase Pro (buy Bitcoin) / Ripio (sell as ARS) with 81.99.