1. Exchanges are indistinguishable from banks.
2. The level of risk can be mitigated with smaller transfers through the intermediary.
3. Creating a fiat ramp to Hive (or any blockchain) on a DEX requires access to a USD API that openly tells us where all the money is going. Which I'm not sure if that exists. It might be possible to opt-in to something like that using an app that directly gets permission from the phone to do things like scan Venmo transfers or notifications. But the attack vectors would perhaps be pretty serious.

I haven't heard of TeraBlock, but Rune has some promise.
Although looking at Thorchain they are already pulling weird shenanigans.
The ultimate breakthrough will always be vendors accepting crypto directly;
even if that means accepting payment on the inevitable black market.