3. I'm confused what you meant. If this service get huge success, on chain transactions may decreased.
You can't send crypto outside the blockchain, it just that the process of sending crypto on SMS is only on the criptolago exchange, where there's no on-chain transaction, you can send and receive crypto if you're registered on the platform and your mobile number is a requirement and connected to the account.
Except the government of Venezuela is just working towards the use of blockchain and somehow centralizing the system.
Every government of any country that will "adopt" cryptocurrency will probably do the same, especially china, for centralization.