Apple doesn't have a similar ban, but told the WSJ that it routinely reviews its App Store rules to "address new or emerging issues."

To no one's surprise, affected lenders aren't happy -- this forces them to either offer lower rates or bow out entirely. Online Lenders Alliance CEO Mary Jackson repeatedly maintained that the companies' practices were allowed, arguing that the ban hurts "legitimate operators" as well as customers looking for "legal loans."

While there won't be too many people mourning the absence of these loans, Google's decision does raise the question of whether store operators should ban apps whose business models are ethically shaky, but still legal. Much like retailers' approaches to e-cigarettes, tech giants may have enough power to decide whether or not entire business categories can succeed.