I think the two main selling points for stablecoins is getting a USD based account in any part of the world, it's a pretty killer app for most countries, just getting out of your local shitcoin is a blessing in itself

Stablecoins are cheaper to remit and do business, not that they are cheap in general, just cheaper than a PayPal or whatever service you're forced to use with tradFI. if your doing cross boarder trades or you work remote stables allow you to settle faster and give up less margin so you can charge cheaper prices locally

Then they also allow provide a global liquid market that you to settle at the same speed as Bitcoin which is great when you finally figure out that fiat isn't worth holding long term. instead of having to find your currency pair to swap into BTC you just get stables and you can buy Bitcoin from anyone in the world