Stable coins are not "crypto" currencies. They have black lists (similar to your bank's fraud department) and they are backed by deposited money (so there is trusted issuer who promises to redeem them for actual cash).

So 2 key features of a crypto-currency are lacking in stablecoins: censorship-resistance and absence of centralized trusted parties.

That you can move them on a blockchain (as long as permitted) with your private key is not much different from signing TLS connection in your Venmo. But with higher fees and latencies.