Plenty of people look back on their early 20s and regret the things they said and did. Few do it as publicly as Mark Zuckerberg.

In a note posted to his social network on Wednesday, the 34-year-old Facebook chief executive of 2019 spent 3,000 words patiently explaining why the 24-year-old Facebook chief executive of 2009 was wrong to build a company predicated on the assumption that we would all want to live every second of our lives in the public sphere.

“People should be comfortable being themselves,” Zuckerberg wrote, “and should not have to worry about what they share coming back to hurt them later.

“People’s private communications should be secure … People should have simple, intimate places where they have clear control over who can communicate with them and confidence that no one else can access what they share.”

It’s a mature, sensible vision of how to build a communications network without inducing crippling anxiety in its users, eroding civil society or creating a private panopticon that erodes the very notion of a personal life. It’s just a tad frustrating that it took Zuckerberg a decade of running the other sort of communications network – the one that does do all those things – to realise that maybe he needed to rethink those issues.

But the problem is that Zuckerberg is very good at thinking large thoughts, and fairly bad at translating them into positive action. In this latest note, there’s only really one concrete change promised, and it’s got as many downsides as upsides: the company plans to unify Instagram DMs, Facebook Messenger and WhatsApp, creating a single encrypted messaging service that links its three largest brands.

There are undoubted positives to the move, first uncovered in January. Unifying the platforms will certainly be more convenient for some of the company’s customers. And end-to-end encryption protects users against mass surveillance – both from nation states and from Facebook itself, which currently has a business model that involves merrily data-mining every message sent on Messenger in order to improve the accuracy of its targeted advertising.

But Zuckerberg’s spin shouldn’t obscure the driving motivation behind the change, which is almost certainly less about high-minded ideals of privacy, and more about pre-empting the attempts from regulators in the US and EU to separate, and maybe even spin-off, the Facebook subsidiaries in an attempt to introduce much-needed competition into the market. If Facebook can argue that the three companies are too commingled to be segregated, it might stand a chance of winning that battle.

‘The company plans to unify Instagram DMs, Facebook Messenger and WhatsApp, creating a single encrypted messaging service that links its three largest brands.’ Photograph: Chesnot/Getty Images

Even if the change would help Facebook’s corporate goals, don’t hold your breath while you wait for it to ship. Zuckerberg has a tendency to announce flashy privacy-focused changes that take years to materialise: from a promise to give users access to the same secret feature he was using to delete already-sent messages, often from years ago (promised April 2018, shipped February 2019 – with a limitation that means it only works within 10 minutes of sending) to a commitment to a “clear history” feature, that would let users wipe the company’s profile of them (promised May 2018, still not available but reportedly coming “later this year”).

Zuckerberg’s big thoughts, then, rarely translate to big actions. Instead, the best way of viewing these pronouncements from on high – from a man who doesn’t need to say anything at all, since he controls well over 60% of Facebook’s voting rights and can never be fired – is an effort to convince all of us to view the world the way Zuckerberg does.

That’s a world in which “interoperability” gets redefined to mean “people should be able to use any of our apps to reach their friends”, and where “privacy” means “there must never be any doubt about who you are communicating with”. For privacy campaigners, Facebook’s creation of huge advertising profiles based on information like phone numbers uploaded for security reasons, who you text and when, or the results of facial recognition scans on public photos, has a little bit to do with that issue as well.

The real question for Zuckerberg is whether he’ll put Facebook’s money where his mouth is. Facebook is an advertising business first and foremost, and one of the most successful ever to exist. But the “privacy-focused” vision Zuckerberg has, even a denuded version of privacy, would wound that business to the core. The endless scroll of a Newsfeed, the passive consumption of an Instagram story, even the immersive experience of an Oculus VR headset, may lend themselves to advertising at scale, but a closed, encrypted, one-to-one messaging app doesn’t.

So whether or not Zuckerberg believes what he’s saying, the fact that Facebook’s stock price is barely changed on the news of Zuckerberg’s note suggests that the people who actually own Facebook don’t. They read that letter, and decided that their money was perfectly safe where it was. From their conclusion, it shouldn’t be hard to draw your own.

• Alex Hern is a technology reporter for the Guardian