[mistersquid]

Agreed. The HN title is misleading and inaccurate, but even the original title obscures the presence of acne in non-Western countries.

For example, many Japanese suffer very bad acne through adolescence and young adulthood. In one study, nearly 60% of the teenagers had acne and many "had seborrhea and a family history of acne." [0] Indeed, even the most basic web search for "acne vulgaris in Japan" yields plenty of results to studies and treatments. (The study linked in the OP does mention Okinawa, whose relationship to Japan is complicated, as having practically zero incidence of acne vulgaris.)

In any case, given the current and historical prevalence of acne in Japan and the assertions of the study in the OP, would Japan be considered Western or is it a condition of urbanization and the health effects due to environment and diet?

Perhaps the word "Western" confounds easy interpretation of this study because it's actually a proxy for "outside Papua New Guinea".

[0] https://www.jstage.jst.go.jp/article/dermatol/111/9/111_1347...

EDIT: clarify source of reference to Okinawa.