Here’s a possible hypothesis: Twitter might not want to look too closely at this problem because then they would have to remove accounts, reducing the number of reported “active users” on the platform. More than 90 percent of Twitter’s revenue comes from advertisers. And it is probably safe to assume that most of these advertisers are paying Twitter to display ads to real human beings, not bots or Russian trolls masquerading as Americans. If Twitter removed more of these inauthentic accounts, it would ding its “active user” metrics, which drive advertising revenue—the source of value for the platform.