I think this would be absolutely brilliant. The ability to readily move data from one service provider to another would provide a much-needed boost for competition in the digital space.
I don't know how common it is, but at least in Finland one can move their mortgage from one bank to another if they get a better deal elsewhere [1]. Or, one can move their mobile phone subscription and keep the old number. I find these kinds of service transfer entitlements essential for efficient competition.
[1] Or technically: one can always pay their Euribor bound mortgage off without extra cost, and take a new mortgage from another bank.