This is essentially your argument just using money rather than data right?
Can you think of any reason someone might like to hold their own data? Perhaps they don't like being at the mercy of a company that can ban you from accessing it at any time like the OP? Perhaps they like the freedom of choosing where they send and receive data from instead of only using the provider approved services?
Crazy that so many people still don't get this and give all their power and control of their money away to providers because it's slighty more convenient.