I see how that's true on a legal level, but if we're just talking about social and public health impacts, I don't see why the distinction between prescription and illegal use matters here. A three-fold increase in a category of drugs with major health impacts seems newsworthy to me. After all, the boundaries between legal and illegal use are far from fixed. Methamphetamine was once widely prescribed by physicians for weight loss, for instance (and is indeed still legally available as a prescription medicine) [1].

Presumably we can agree that a world in which prescriptions for methamphetamine have tripled might be a cause for concern, right? It's debatable whether this class of drugs has the same abuse and health risks, but based on my own reading and anecdotal experiences, I think they're pretty comparable.

[1] https://resobscura.blogspot.com/2012/06/from-quacks-to-quaal...