Encouraging the deletion of old posts is still a bad thing for the internet. A lot of in-depth subject knowledge is contained in old internet posts.

I don't think I support an unlimited right for people to delete everything they've posted to the internet. Previous law did not recognize one; the primary mechanism for attempting to assert one would likely be copyright, and a clickwrap user agreement would usually offer sufficient protection for the forum operator.

And more generally, prior to GDPR, a person could casually put up a forum on a website and not have a meaningful legal compliance workload. GDPR changes that.