It's not a property of a regulated market, it's a property of a specific centralized system. Nothing prevents SEC from "regulating" a system where such rollback

It's not a property of a regulated market, it's a property of a specific centralized system. Nothing prevents SEC from "regulating" a system where such rollback is impossible, and nothing prevents centralized cryptocurrency exchanges from rolling back transactions that haven't made it into blockchain. There can even be non-immutable blockchains, which rollback mistakes, such as Ethereum.