Two and a half years ago, Fortune published a cover story, “The Age of Unicorns.”

This was something of a noble statement, because even then we were well past peak unicorn, and yet the beast needed to be trapped inside the stapled mundanity a magazine cover to be tamed. The Silicon Valley unicorn had gone from clever buzzword to very real trend to something wild that felt just a little bit out of control. Or as Fortune explained it...