Klarna can also be used for payments directly from your bank account. They probably didn't have another platform for handling that internationally. Much nicer than using a bank card for the payment!

(Well, okay: That site has elected to disable that feature. I tried choosing Helsinki, Finland as delivery location and payment by Klarna, and all I got was this:

Kiitos kun harkitsit Klarnaa

Arvostamme kiinnostustasi fiksumpaa maksutapaa kohtaan. Valitettavasti joustavat maksuvaihtoehtomme eivät ole juuri nyt saatavilla tällä alueella tai tälle valuutalle.

Tiedämme, ettei tämä ole paras mahdollinen tilanne, mutta toivomme pian tarjoavamme maksuvaihtoehtojamme useammissa paikoissa.

So, they don't want to use Klarna for what would actually be a fair and sensible thing, only for the bad stuff. Heh.)