Having spent endless hours trying to figure out the best path to GDPR compliance,
I totally agree with Nicolas: there has to be one single, integrated solution for the end-user who wishes to view, edit, delete, or download ALL their personal data, which was submitted voluntarily, or collected automatically in our sites (such as the user profile, forum posts, comments, Hikashop profile, IPs, and so on). Unfortunately Joomla is not ready yet. It should have been ready, but GDPR was probably neglected or underestimated.
Nevertheless May 25 is approaching and we must comply with GDPR's requirements. Please correct me if (or where) you think I am wrong:
The GDPR sets the rights of the data subjects (right to erasure, portability, rectification, etc) and requires us to provide the means to the data subjects to perform all these rights. Until the Joomla team comes up with a solution, we must provide one. One way is to look for such software (Joomla components) from 3rd parties, which deal with GDPR. Some of these software solutions are very good, yet they don't fully comply with all requirements.
Another solution (which is perfectly acceptable in my opinion) is the following:
You can create a new email account dedicated to privacy issues (e.g. privacy @ yoursitename.com). Then you must add a section to your Privacy Policy page (called e.g. 'Your Access to and Control over your personal information'), where you inform visitors about all their rights to their personal information, and tell them that they can reach you in this email address if they wish to perform any of these rights. As an additional step, you may create a dedicated contact form e.g. on your site footer, which includes various checkboxes corresponding to the users' rights to information.
Of course this means more work for us. I don't think there will be so many request of this kind to keep us very busy. Or so I hope.