Can't that be a violation in the eyes of GDPR? If they don't give users a simple button, then can't that be argued to be not giving the user the ability to export data. The problem I have with GDPR is that there's so much open to interpretation.
Source: https://ico.org.uk/for-organisations/guide-to-the-general-da...
Edit: mis-referenced article 15 as export instead of access.