Earlier quoted context omitted.
It's not so easy. Someone buys a book. Transaction is recorded, and now we know total book sales. Someone says "delete me and my purchases", so you do, and oops - total book sales are now wrong. There's ways around it, obviously. But they are not easy. Much easier to just mark as deleted. Another example: Threaded conversation - someone deletes their post, and oops all the replies are now orphaned.
More GDPR strawmen. If a user requests deletion, assign anyYassociated entities (eg purchases, conversations etc) to an anonymous user. Or, keep the original user record and just blank all of the fields. You've had two years to think about these problems.
Edit:
Ok, looks like there is a clause for these scenarios:
"However, the further retention of the personal data should be lawful where it is necessary, for exercising the right of freedom of expression and information, for COMPLIANCE WITH A LEGAL OBLIGATION, for the performance of a task carried out in the public interest or in the exercise of official authority vested in the controller, on the grounds of public interest in the area of public health, for archiving purposes in the public interest, scientific or historical research purposes or statistical purposes, or for the establishment, exercise or defence of legal claims."
Then there's:
"It should not apply where processing is based on a legal ground other than consent or contract. By its very nature, that right should not be exercised against controllers processing personal data in the exercise of their public duties. It should therefore not apply where the processing of the personal data is necessary for compliance with a legal obligation to which the controller is subject or for the performance of a task carried out in the public interest or in the exercise of an official authority vested in the controller."
And, in terms of technical burden at least it seems like they try to alleviate it somewhat...
"The data subject's right to transmit or receive personal data concerning him or her should not create an obligation for the controllers to adopt or maintain processing systems which are technically compatible"