A lot of people are really afraid of using cryptocurrencies only because of their high volatility, and stablecoins aren't so popular yet.
And that's why Rockstable team is making their project. There are so many unbanked people or people who use fiat for remittance.
"We serve the unbanked by introducing ROKS and spreading its usage as medium of exchange."is said on their site, but i don't understand why do you think unbanked will use cryptocurrencies instead?