Whether they’re doing it on purpose is not relevant to the legal aspect of the situation. They have a responsibility to honor deletion requests. If a user complains, the appropriate response is “sorry you had a problem, we’ll fix it,” not “sorry, we will only honor our legal responsibilities if you follow our preferred [but not stated until now] procedure for requesting deletion, try again.” Having database problems opens you up to legal liability whether you like it or not, and trying to convince users that you are not responsible for your own database is… inappropriate.
Besides, there have been bugs with manual deletion, too. This is at least partly a problem with their own systems.