The main purpose with the creation of digital currencies was to make able the transactions for using the coins for payments without going through a bank or an organization that controls the coins. This is the purpose of decentralized currency. Actually this has turned out in a very different way, but the way that the example that you give works directly with bank through making deposits on them to make payments via sms or somehow. That's why it's so well adopted, because banks permit that. The point for digital currencies would be that payments are allowed by banks anonymously, which is quite far away to happen, basically because they wouldn't know who to charge taxes to as they normally work together with tax governments. And the volatility of the coins is way loong far away to become stable as they are under no regulation. So if this was permited with no regulation maybe you pay a bill of 50 dollars which turns out to be 25 $ the next they for the bank. If they want to make it, they will have to regulate it and permit it which won't be too bad for altcoins depending on how far they go with regulations and how much we let them go with them. Once you let the big ones come in the game, we are fucked, they start to shake your hand and finally they will eat your arm faster than you realize.