Are you suggesting that WhatsApp's model of organization is the norm for a sustainable organization? I think it's a clear outlier in many respects.
Are you suggesting that WhatsApps business model was based on annual revenue?
Since WhatsApp was a revenue-generation corporation with a board of directors, like any other corporation, before their acquisition, and since I don't like to indulge in conspiracy theories, I'm going to assume that yes -- their business model was based on annual revenue.
Then you'd assume wrong. The goal of the board is to maximize return for investors. In WhatsApp case, it's not hard to see that their goal was to grow as fast as possible, revenue be damned, so they could be a very attractive takeover target for a company like Facebook who could eventually hope to monetize that user base.
Silicon Valley mentality at its finest.
The company existed to make a return for the owners. The owners exited with $16 billion. That was the motivation of the owners/employees, not $14 million in annual revenue.
My point is that the transaction must be analyzed from the viewpoint of the owners (as that is what the poster I was responding to cared about, viz a viz total profit/revenue to Twitter). When you do that, WhatsApp cashed (well, assuming FB stock can be treated as cash) out more per employee than Twitter.