Before the first top tech company executive took his or her seat around the marble conference table at Trump Tower on Wednesday, Donald Trump had already made his point, loud and clear.

Apple CEO Tim Cook, Alphabet CEO Larry Page, Amazon CEO Jeff Bezos, Facebook COO Sheryl Sandberg -- none of them learned anything they didn't know from the president-elect, or offered any radical new ideas about how to create jobs, the putative focus of the meeting.

But that didn't matter, because it wasn't the real purpose of the event.

The real purpose was best illustrated by who wasn't there: Jack Dorsey, the co-founder and current CEO of Twitter, and also CEO of the payments company Square. As everyone in the room was no doubt aware, Dorsey wasn't there because he wasn't invited. Just why was a mystery, all the more mysterious because Twitter is the one piece of technology that Trump, otherwise something of a Luddite, unabashedly adores, while Square is used by millions of small businesses and independent vendors.

A Forbes reporter was told Twitter didn't have enough impact on the economy or employ enough people to rate an invite. Trump lent that some credence when he said Peter Thiel, the venture capitalist serving as his top transition-team adviser on technology, had told him not to invite at least one company that was "too small." A board member of Twitter rival Facebook, Thiel has publicly disparaged Twitter on multiple occasions.

But another source says Dorsey's interview with Edward Snowden on Tuesday was the reason for the snub; Snowden is considered by many, especially on the political right, to be a traitor. Thickening the broth still farther, Politico reported that Trump decided to punish Dorsey for vetoing his campaign's plan to create a "Crooked Hillary" emoji for appending to Tweets. And of course Twitter was the first tech company to step forward and declare it would never go along with Trump's tossed-off idea of a national registry for Muslims.

These explanations aren't mutually exclusive. It doesn't matter if all of them are true or none of them is. What matters is, Trump had an opportunity to make an example of someone, and he did.

Ever the dealmaker, at least in his own mind, Trump is always working one of two tools: the carrot or the stick. He's either flattering or berating, conciliating or demonizing. You saw that a few weeks ago, when he reportedly dressed down a delegation of prominent television journalists and executives,* then showed up the next day at the New York Times and called the newspaper he loves to hate a "great, great American jewel."

Trump has already done his share of beating the tech industry with his rhetorical stick. He threatened to go after Bezos, whose Washington Post has published scoop after damaging scoop about Trump, on antitrust grounds, and promised to force Apple to start making iPhones in the U.S.

All that was left, in person, was to offer the carrot -- but not too indiscriminately. That would be rash, for Silicon Valley is perhaps the only remaining American power center with the economic and cultural capital to challenge Trump and Trumpism.

So there was flattery aplenty -- "In the world, there's nobody like the people in this room, and anything we can do to help this go along, we'll be there for you," he told his audience of captives -- and vague promises to "make it a lot easier for you to trade across borders" and the like.

But none of it carried anything like the weight of the implied threat Trump hung in the air by excommunicating Dorsey. The vaguer or more trivial Dorsey's sins, the better for Trump's purpose of striking fear. The clear message:

You aren't any different. You are used to being treated with deference because of who you are and what you've done, and you're used to politicians who engage with you through the appropriate channels, ever mindful of official decorum and conflicts of interest. Forget all that. It won't save you. If you are good to me, I'll be good to you. If you cross me, I will single you out and humiliate you just like I humiliated Chris Christie and Marco Rubio and Jeb Bush and Mitt Romney. I will give you the full Trump treatment, and it's a lot worse than forcing you to sit at the table with my children as though they are your peers, you, the new masters of the universe.

On their way out of Trump Tower, none of the tech executives stopped to answer questions from the press pool.

Because his message was received.

*An earlier version of this story said Donald Trump "publicly dressed down" television journalists and executives. The report cited described a meeting that, while well attended, took place in a private setting. "Publicly" has been changed to "reportedly."