The stable coins are a great tool for speculators and for arbitrage. And.. that's all.
They serve a small but important purpose. USDT does exactly what people want it to do. It enjoys so much global adaption within this ecosystem, that it's probably the only token that's actually used the way it should be used.
So it all comes to the trust in the issuer, in the same way you have to trust your country's central bank for fiat.
I personally don't trust them - neither my central bank, neither the stable coins issuers.
People don't trust Bitfinex either, yet continue to use USDT to such degree, that it generates twice as much volume as there are tokens in circulation. If that isn't actual utility then I don't know what is.
USDT is subject to a constant dose of shit and fud, yet it still manages to remain on top of the industry. I'm not saying it's a fantastic addition to this industry, find it shady to a certain degree, but it works and that's what matters.