Would potentially be useful if you could take advantage of this _after_ you've been excommunicated from a service for whatever unknowable violation you committed.
The data subject shall have the right to receive the personal data concerning him or her, which he or she has provided to a controller, in a structured, commonly used and machine-readable format and have the right to transmit those data to another controller without hindrance from the controller to which the personal data have been provided
Would you be able to trust GDPR to actually return “useful” data?