In April 2017, an “Amazon Competitor Deep Dive” looked at what Amazon’s early results in Japan might mean for Play as a whole — pointing out that while Amazon’s Appstore had grown to 1 to 2 percent of Play users, it might account for as many as 20 percent of High Value Users (the “whales” who spend big money on in-app purchases in their favorite game titles).

Amazon didn’t want to lose paying users. A couple juicy passages (bolding Google’s):

Bad news: We face the risk of becoming a “showroom” for Amazon or other apps stores.

Good news: Amazon yet to establish critical mass. We have an opportunity to react before this happens.